Let’s do some sleep math. You lost two hours of sleep every night last week because of a big project due on Friday. On Saturday and Sunday, you slept in, getting four extra hours. Come Monday morning, you were feeling so bright-eyed, you only had one cup of coffee, instead of your usual two. But don’t be duped by your apparent vim and vigor: You’re still carrying around a heavy load of sleepiness, or what experts call “sleep debt”—in this case something like six hours, almost a full nights’ sleep.
Sleep debt is the difference between the amount of sleep you should be getting and the amount you actually get. It’s a deficit that grows every time we skim some extra minutes off our nightly slumber. “People accumulate sleep debt surreptitiously,” says psychiatrist William C. Dement, founder of the Stanford University Sleep Clinic. Studies show that such short-term sleep deprivation leads to a foggy brain, worsened vision, impaired driving, and trouble remembering. Long-term effects include obesity, insulin resistance, and heart disease. And most Americans suffer from chronic deprivation.
A 2005 survey by the National Sleep Foundation reports that, on average, Americans sleep 6.9 hours per night—6.8 hours during the week and 7.4 hours on the weekends. Generally, experts recommend eight hours of sleep per night, although some people may require only six hours of sleep while others need ten. That means on average, we’re losing one hour of sleep each night—more than two full weeks of slumber every year.
The good news is that, like all debt, with some work, sleep debt can be repaid—though it won’t happen in one extended snooze marathon. Tacking on an extra hour or two of sleep a night is the way to catch up. For the chronically sleep deprived, take it easy for a few months to get back into a natural sleep pattern, says Lawrence J. Epstein, medical director of the Harvard-affiliated Sleep HealthCenters.
Go to bed when you are tired, and allow your body to wake you in the morning (no alarm clock allowed). You may find yourself catatonic in the beginning of the recovery cycle: Expect to bank upward of ten hours shut-eye per night. As the days pass, however, the amount of time sleeping will gradually decrease.
For recovery sleep, both the hours slept and the intensity of the sleep are important. Some of your most refreshing sleep occurs during deep sleep. Although such sleep’s true effects are still being studied, it is generally considered a restorative period for the brain. And when you sleep more hours, you allow your brain to spend more time in this rejuvenating period.
As you erase sleep debt, your body will come to rest at a sleep pattern that is specifically right for you. Sleep researchers believe that genes—although the precise ones have yet to be discovered—determine our individual sleeping patterns. That more than likely means you can’t train yourself to be a “short sleeper”—and you’re fooling yourself if you think you’ve done it. A 2003 study in the journal Sleep found that the more tired we get, the less tired we feel.
So earn back that lost sleep—and follow the dictates of your innate sleep needs. You’ll feel better. “When you put away sleep debt, you become superhuman,” says Stanford’s Dement, talking about the improved mental and physical capabilities that come with being well rested. Finally, a scientific reason to sleep in on Saturday.


“Catching Up” On Sleep

Snoozing more on weekends isn’t really the solution.

Whether you find yourself staying up late to finish a project for work, order a second glass of wine with friends, or watch late-night TV, it’s easy to miss your bedtime. But even an hour or two of lost sleep every night quickly adds up over the course of a week.

Unfortunately, sleeping in for an hour or two on Saturday and Sunday mornings doesn’t really make up for all that lost time, even if you feel better on Monday in the a.m. All of that sleep deprivation leads to something called “sleep debt”—the difference between the amount of sleep that you need and the amount that you’re actually getting. Have more questions about sleep debt? We answer the most burning ones.

Q: Besides feeling tired, what are the other consequences of sleep debt?

A: The potential short-term, negative effects include a foggy brain, impaired driving, difficulty remembering things, and reduced vision, while potential long-term ramifications include heart disease, obesity, and insulin resistance.

Q: Why isn’t sleeping in on the weekends enough for catching up?

A: Though you may feel more rested on Monday morning, that extra shut-eye doesn’t erase all of the drawbacks from not catching enough zzz’s during the week. While extra weekend sleep does help reduce daytime sleepiness and stress, your ability to focus and pay attention will still be reduced. It can also throw off your internal body clock (also known as your circadian rhythm) and lead to Sunday night insomnia. However, you can eventually bounce back once you’ve adapted to a steady schedule that gets you enough winks.

Q: Can napping help reduce sleep debt?

A: After a sleepless night, a nap the next day can help reverse some of the negative effects of sleep deprivation. Taking one in the early-to-mid afternoon is best (since a nap later in the day might interfere with falling asleep at bedtime). While are helpful once in a while, they’re only short-term solutions. Don’t depend on them regularly to get you back on track. Ultimately, getting enough sleep at night is the answer.

Q: Do napping and sleeping in on weekends have downsides?

A: Yes, eventually they could disrupt your circadian rhythm, making it even harder to fall asleep at night. Though you’ll feel more rested after waking up late on Sunday morning that will make it harder to doze off at bedtime that night, which creates a bad cycle.

Q: Can you ever really catch up on sleep?

A: Yes, you can do that by ultimately getting back on a regular cycle of seven to nine hours of shut-eye per night. It can take days or even weeks for your body to return to a normal pattern. In the meantime, if you’re trying to make up for lost time, go to bed early and wake up at your normal time instead of sleeping in late. To get your circadian rhythm back on track, avoid bright lights before bed and keep your bedroom as dark as possible. Get back on schedule by going to sleep a few minutes earlier every night until you’re back to your regular bedtime. Taking melatonin can also help you doze off at the right time. Also, avoid eating, drinking and exercising right before you hit the hay.

Sleeping in late on a Saturday sounds delicious, right? However, as with many delicious things, there may be a cost to your health and waistline.

Catching up on sleep on the weekend can almost feel like the norm these days. With increasingly full schedules and competing demands, sleep is often sacrificed during the busy workweek. As the week comes to an end, many people look to the less structured weekend to cram in what couldn’t be done during the week, including sleep. In sleep clinic, I now ask “When do you get up on work (or school) days?” and “What about bedtime and wakeup time on days off?” The catch-up time — perhaps a 6 am wake-up for a workday, but 11 am on a weekend — can be close to an entire weeknight’s sleep. But does it matter? We’re paying back our sleep debt, right?

Our average hours of sleep may hide a weekly sleep debt

Despite the fact that number of hours of sleep, when averaged, may approach the seven to nine hours per night recommended by most professional societies, the “average” can hide some truths. The daily amount, quality, and regularity of bed/wake time all seem to matter too. A recent paper in Current Biology shows that our sleep is not very forgiving of being moved around to more convenient times. Researchers found that subjects who cut their sleep down by five hours during the week, but made up for it on the weekend with extra sleep, still paid a cost. That cost included measurable differences: excess calorie intake after dinner, reduced energy expenditure, increased weight, and detrimental changes in how the body uses insulin. Although sleep debt was resolved on paper, the weekend catch-up subjects had similar results (though there were some differences) to those who remained sleep-deprived across a weekend without catch-up sleep.

New research is a reminder that you can’t cheat on sleep and get away with it

First, sleep deprivation, even if only during the workweek, likely has real health consequences. Sleep is often an overlooked factor when considering chronic disease risk, including hypertension, diabetes, heart disease, and even death. There’s ample data, including a recent review in Sleep Medicine, suggesting that too little sleep is a risk factor for these conditions, as well as obesity. Unfortunately, this new study suggests that extending sleep on the weekend doesn’t seem to undo the impact of short sleep.

Second, whether the health impact is due to the decreased sleep alone, or additionally due to changes in timing of sleep on the weekend — an at-home “jet lag” — is unknown. The impact of essentially jumping time zones by staying up later and sleeping later on weekends, may add to the problem. Other behaviors, such as eating or drinking later on weekends, also confuse the body’s rhythm.

What can you do to improve nightly sleep?

As with a lot of medicine, prevention seems to be the best strategy. Although we can’t undo the impact of short sleep by trying to oversleep on the weekends, we can try to carve out a bit more time for sleep at night during the week and improve behaviors that lead to better sleep.

It’s very important to keep bedtime and waketime fairly stable across the weekend, which may also help reduce the jet-lag effect. Short naps of 15 to 20 minutes may help relieve sleepiness, but shouldn’t interfere with the regularity of bedtime and waketime. For some people, keeping a sleep log to track sleep patterns can be eye-opening and provide accountability, in the same way that tracking food choices and behaviors around eating can help with weight loss. Finally, consider reframing your relationship with sleep and prioritize it. Sleep is preventive medicine — we know it helps reduce illness and optimizes your daily well-being.

Getting extra sleep to overcome sleep deprivation may seem like the right thing to do, but a recent Harvard Medical School study found that it’s not that easy.

The study highlights the effects of chronic sleep loss on performance and demonstrates that it is nearly impossible to “catch up on sleep” to improve performance.

According to the study, even when you sleep an extra 10 hours to compensate for sleeping only 6 hours a night for up to two weeks, your reaction times and ability to focus is worse than if you had pulled an all-nighter. This is not good news for shift-workers such as doctors, truckers, and law enforcement officers.

The bottom line is that there is no real way to recoup lost sleep. There are things shift workers can do to get quality sleep during their off hours, for example, wearing dark glasses to block out the sunlight on your way home, keeping the same bedtime and wake time schedule, even on weekends, eliminate noise and light from your sleep environment (use eye masks and ear plugs).

  • Get more sleep tips for shift workers.
  • Learn more about the Harvard Medical School study

Can you catch up on sleep?

New research has looked at the health impact of lie-ins at the weekend. The Daily Telegraph reports they “boost brain power”, the Daily Mail says dragging a teenager out of bed could be detrimental to their health, while BBC News warns that one lie-in won’t make up for poor sleep during the week.

The study behind this news used a range of tests to investigate alertness and sleepiness after five consecutive nights of sleep deprivation and a single night of “recovery sleep”. When the length of this recovery sleep was increased up to the maximum of 10 hours, participants showed the greatest improvement in mental functioning. However, their mental performance proved to be not as strong as it had been prior to sleep deprivation.

This was well-conducted experimental research that has furthered our understanding of the physiology of sleep. However, as a laboratory study it is unclear how relevant it is to sleep patterns in everyday life. Furthermore, all the participants had normal sleep patterns prior to the research, so its results do not apply to people with chronic sleep problems such as insomnia, or to people who normally work at night.

Where did the story come from?

Researchers from University of Pennsylvania and University of South Australia conducted this study, which was published in the scientific journal, SLEEP. The study was reported to be not industry-funded, although individual researchers received funding from various commercial organisations.

BBC News, reporting that a lie-in at the weekend does not make up for lack of sleep during the week, has probably reflected the findings of this research most reliably. Many of the news sources headlining improved health with a lie-in have not taken into account the many limitations within the artificial sleep scenario used in this research.

What kind of research was this?

This was an experimental study designed to investigate the effect of increased sleep duration for a single night after a period of chronic sleep deprivation.

The researchers conducting this study looked at how sleep patterns affect the recovery of neurobehavioural functioning, as the effects upon brain function of poor sleep during the five-day working week are said to have been rarely studied. The research aimed to establish the “dose-response relationship”, i.e. the duration of sleep needed to produce a recovery in certain brain functions, such as reduced sleepiness, faster thinking or improved mood.

What did the research involve?

The researchers recruited 171 healthy adults aged between 22 and 45 for participation in a 12-day study conducted in a controlled laboratory environment. The subjects all had normal sleeping hours of between 6.5 and 8.5 hours a night, with no sleep disturbances or medical or psychological conditions.

For the first two nights, all participants could sleep for up to 10 hours, and then for the following five nights the participants had their sleep restricted to four hours per night. They were then randomly assigned to have a recovery night of sleep, at one of six sleep doses: zero, two, four, six, eight or 10 hours. The sleep regimes on the four remaining nights of the 12-night study were not reported. Seventeen of the subjects had also been randomised to join a control group, in which participants could continue to sleep for 10 hours on all of the study nights. Sleep times appear to have been controlled mainly through levels of light in the study laboratory.

The subjects received regular nursing assessment throughout the trials. They wore a wrist actigraph (monitoring device) throughout the study to gauge their physical activity, with brain activity measured using ambulatory EEG devices worn continuously for several study days.

During waking hours the main neurobehavioural outcomes were assessed through performance on a number of recognised scales of awareness and functioning. The Psychomotor Vigilance Test looked at how brain function related to physical movement, subjective sleepiness was tested using the Karolinska Sleepiness Scale and physiological sleepiness was assessed on a modified Maintenance of Wakefulness Test.

The researchers also looked at secondary outcomes of psychomotor and cognitive speed as measured on the Psychomotor Vigilance Test and the number of correct answers given on the Digit Symbol Substitution Task. Subjective fatigue was assessed on the Profile of Mood States test.

The researchers then looked at how neurobehavioural outcomes following the recovery night’s sleep were affected by each of the sleep doses ranging from 0–10 hours.

What were the basic results?

A total of 159 people completed the study: six withdrew due to personal reasons (mainly time commitment) and six due to mild adverse effects of sleep deprivation.

The researchers found that as the dose of recovery sleep increased there were corresponding increases in:

  • total sleep time
  • stage 2 sleep (an early stage of deep sleep)
  • REM sleep (a phase of sleep where the eyes move rapidly)
  • non-REM slow wave energy (a particular phase in deep sleep during which REM is not seen)

Performance in the Psychomotor Vigilance Test and Karolinska Sleepiness Scale tests of neurobehavioural function increased exponentially with each increasing dose of recovery sleep, i.e. there was a sudden great improvement in these outcomes at the higher sleep doses. Performance in the Maintenance of Wakefulness Test increased as recovery sleep dose increased.

When they compared the effects of the recovery sleep following sleep deprivation they found that neurobehavioural function (as measured on the Psychomotor Vigilance Test, the Karolinska Sleepiness Scale and the Profile of Mood States test) was not as good as it had been at baseline prior to sleep deprivation, or compared to those who had slept for 10 hours every night of the study.

How did the researchers interpret the results?

The researchers conclude that neurobehavioural deficits induced by five consecutive nights of sleep deprivation were improved with an increased dose of recovery sleep, with much of the deficit recovered by 10 hours of recovery sleep. They say that complete recovery from such sleep restriction may require either a longer period of sleep on one night or multiple nights of recovery sleep.


This is well-conducted experimental research that has furthered our understanding of the physiology of sleep. It aimed to investigate how alertness and sleepiness were affected by five consecutive nights of sleep deprivation followed by a single night of recovery sleep. As the length of recovery sleep was increased up to the maximum of 10 hours, there was increasing improvement in neurobehavioural function. However, even then, performance on a range of tests was not as great as it had been prior to the deprivation.

There are a number of considerations and limitations that must be made when interpreting these results:

  • All of the recruited subjects were healthy adults with work and lifestyles that did not cause them to be sleep deprived in their normal daily lives. They also had no medical or psychological conditions. Therefore the results cannot be applied to people who suffer from insomnia or sleep deprivation for any identified reason.
  • This was an artificial scenario where the subjects lived in a controlled laboratory environment for 12 days. The situation can therefore not be considered directly comparable to normal life. In particular, controlling duration of sleep through laboratory lighting may not have accurately limited or extended sleep to the number of hours assigned to each participant. Crucially, these patterns of sleep cannot be considered to be the same as when a person knows they have to wake and get out of bed for a specific reason, such as going to work.
  • The study only examined the situation of five days’ sleep deprivation followed by one recovery sleep, which cannot inform upon the longer-term effects upon health or wellbeing when this is a regular pattern, as may occur for many working individuals (particularly night-shift workers).
  • Although the overall study was reasonably large, the participants were spread across six recovery sleep groups and a control group. This meant that there were relatively small numbers of participants in each group.
  • Direct effects of a lie-in upon health, as headlined by the majority of newspapers, have not been assessed in this study, which only assessed certain measures of brain function and physiological performance.

Analysis by Bazian
Edited by NHS Website

Links to the headlines

Lying in at the weekend boosts your brain power, study shows

The Daily Telegraph, 2 August 2010

One lie-in ‘not enough to counter sleep loss’

BBC News, 2 August 2010

Lie-ins are ‘good for your health’

The Independent, 2 August 2010

Seven hours is perfect sleep length for health

Daily Mirror, 2 August 2010

Now there’s an excuse: Scientists find a weekend lie-in can be good for your health

Daily Mail, 2 August 2010

Links to the science

Banks S; Van Dongen HPA; Maislin G; Dinges DF.

Neurobehavioral dynamics following chronic sleep restriction: dose-response effects of one night for recovery

SLEEP 2010;33(8):1013-1026

Sleep debt: can you catch up on lost sleep?

We’ve all thought it: this weekend, I’m staying in to indulge in some couch time and catch up on lost sleep.

Maybe you did that last weekend, when you woke up early on Sunday morning. But, instead of getting up, decided to rest a little longer with the hope of catching up on sleep you lost thanks to a few late nights last week.

But can you actually catch up on lost sleep?

To answer this, we need to look at sleep debt – what it is, how it is accrued and how do we, so to speak, “pay it back”?

What is sleep debt?

Sleep debt is the cumulative effect of insufficient, poor quality or reduced sleep, regardless of its cause.

The most alarming part of sleep debt is that we accumulate it even when we don’t know it. Even just a few minutes over the course of a week – something you generally wouldn’t even think twice about – can quickly build up into hours.

How is sleep debt accrued?

45 minutes here, an hour there – losing a bit of sleep doesn’t seem like such a big deal. But it’s when those minutes turn into hours that sleep debt starts to build up.

And the longer you leave it, the harder it is to pay back.

To put it into context, here’s a simple example:

Say you generally go to sleep at 10pm and get up around 7am every weekday morning. This week, however, you were out late on three occasions, and didn’t go to sleep until around midnight each night. You still had to get up at 7 the next day, so, after just one week, you’re six hours in debt.

You might think an extra hour or two in bed on Sunday morning might solve your sleepiness, but a simple calculation tells us you will still be four of five hours in debt. And the longer you leave it, the harder it is to pay back.

Sleep debt eventually turns into sleep deprivation, bringing along with it a slew of physical and mental impairments.

How does sleep debt affect us?

Fatigue or drowsiness, does not feel good – especially when you have a demanding schedule. Heavy eyelids, an aching body and the inability to concentrate at work means your day drags and you are often unable to get on top of even the most basic tasks.

Mental fatigue

When we are tired, our mental state suffers, too.

At work, with the kids, or in the car – fatigue can hit us anywhere. If you’re struggling to type word after word on the computer or you can’t quite seem to remember how you got to this intersection while driving home from work, you’re putting yourself (and others) at risk.

You might also suffer from:

  • Poor concentration
  • Daytime sleepiness
  • Short-term memory problems
  • Anxiety
  • Irritability

How do you repay sleep debt?

Temporary payments

Just like someone would cross their fingers and hope that a bounced cheque can buy them a little more time, there are a few temporary things people do to delay sleep and postpone paying back their sleep debt.

These payments, however, are short-lived and are not sustainable:

Drink coffee – a temporary fatigue/drowsiness fixer, caffeine can help you feel more energised, but only momentarily

Move – get up from your desk, take a walk around, or pound the pavement for ten minutes

Take a power nap – Set aside 15 minutes to completely switch off from your phone, work, kids, whatever – and just rest

Put on your favourite music – it might help energise you and pep you up

Catch up on lost sleep: it’s harder than just a “good night’s sleep”

While the final judgment hasn’t been reached on whether you can or cannot catch up on lost sleep, what we do know is that repaying sleep debt isn’t as simple as having a sleep in on Saturday morning.

Just half an hour of reduced or disturbed sleep per night equals three-and-a-half hours of sleep deprivation per week. Before you know it, a month has passed, and you’re already 14 hours behind what your body needs. One Sunday morning sleep in won’t repay that. (And even a phenomenal eight-hour sleep still leaves you six hours in debt!)

Consistency is key

Before you think you can offset one bad night’s sleep with good sleep the next night, remember that good quality sleep as well as good sleeping habits can’t become routine overnight. You’ve got to work hard towards creating a sustainable sleep routine that provides you with the rest you need.

Good sleeping habits include:

  • Going to sleep and waking up at roughly the same time every day (yes, even on the weekend!)
  • Listening to your body: allow yourself to naturally wake up without an alarm clock (this can really tell you how tired you are)
  • Avoiding bright light from TVs, laptops and smartphones right before bed
  • Creating a “wind-down” routine that allows you to feel calm and relaxed before sleep
  • Upgrading your pillows or mattress if they are affecting your sleep
  • Avoiding coffee, alcohol or cigarettes at night

Worried about employees racking up a big sleep debt?

Research has proven well-rested workers are more productive, make fewer mistakes and take fewer sick days. And even if you are encouraging your workers to sleep the required hours when they aren’t at work, how can you ensure they are showing up to work well-rested?

Some companies are now addressing this by paying their employees to sleep more. Through wearable technology employees can volunteer to have their sleep tracked and after a certain number of nights of seven or more hours sleep, they can earn a bonus payment. The CEO says this additional sleep will positively affect the company’s bottom line.

Your employees are your best assets, and if they aren’t getting enough sleep, or their job entails monotonous tasks they may be in danger. So why on earth wouldn’t you protect them from the dangers of drowsy driving and sleep debt?

Sleep debt. Can you catch up on lost sleep?

Routinely losing sleep?

Find out the best way repay your sleep debt…

Getting enough sleep is central to living your best life—from staying safe on the road to being productive on the job. Adults need between 7-9 hours of sleep per day. So, what happens when you don’t make your sleep quota for the day and routinely lose sleep? These lost sleep hours accumulate and are known as your sleep debt. It’s a deficit that grows every time we skim some extra minutes off our nightly shut eye, and it adds up. Getting just two to three hours too little sleep for a few nights can have the same effect as pulling an all-nighter.

Over time those deficits can take a toll on your health, resulting in a lack of concentration, impaired judgment, irritability and longer-term effects including obesity, high blood pressure and heart disease. When you’re in the grips of sleep debt, you often don’t even remember what it’s like to feel well rested, so you may not realize just how tired you are.

So what do you do if you’ve spent weeks or even years of your life logging fewer hours of sleep than you need? Just like with a credit card or a mortgage, sleep debt eventually has to be repaid. And the more you add to it, the bigger your balance. Unfortunately, sleep debt cannot be fully repaid by just one long extended slumber or a quick nap during the day. When it comes to paying down sleep debt, slow and steady is the way to go.

What is your sleep debt?

Sleep debt is the difference in the amount of sleep your body requires to function well versus the amount of sleep you are actually getting. The first step in tackling sleep debt is to know how to calculate yours. Experts agree that most people require around 7-9 hours. Once you’ve determined how much sleep you really need, subtract this from the amount of sleep you’re actually getting and this is your sleep debt. Not sure as to how much sleep you’re getting? Try a sleep journal to log your hours. Once you’ve determined your sleep debt, factor it into your daily schedule.

Establish a regular sleep routine and make gradual adjustments

You won’t be able to change your sleep schedule overnight. The most effective tactic is to make small changes slowly. Try to go to bed and get up at the same time every day – even on weekends! If you’re trying to go to sleep at 10:00pm, rather than midnight, for example, try this: For the first three or four nights, go to bed at 11:45pm, and then go to bed at 11:30pm for the next few days. Keep adjusting your sleep schedule like this. By working in 15-minute increments, your body will have an easier time adjusting.

Establishing a regular sleep schedule and sleeping a consistent 7-9 hours a night both during the midweek and on the weekend is your best way to make-up for sleep debt. Avoid trying to make up for it by sleeping in on weekends. Sleeping in too much on weekends can actually do more harm than good, throwing off your circadian rhythm – the 24 hour body clock that tells your body when to rest, and when to wake. This can make it harder to fall asleep on Sunday night.

If you find it hard to keep a sleep schedule, try our free sleep planner.

Be careful with day time naps

Like sleeping in on the weekends, napping can be a quick way to lop a few hours off your sleep debt. But also like sleeping in, if you nap too long in the afternoon, you might have trouble falling asleep at night. To avoid this, keep your naps short and sweet. A 20-to-30-minute nap, ideally between 2:00pm and 3:00pm is sufficient enough to make a dent in your sleep debt. Just keep in mind that while naps are helpful, they’re only short-term solutions. Don’t depend on them regularly to get you back on track. Ultimately, getting enough sleep at night is the answer.

When it comes to repaying your sleep debt, observe and follow your innate sleep clock. It might take time to adjust your lifestyle, but the payoff of attacking each day with the sleep you need is worth it. It can take days or even weeks for your body to return to a normal pattern or for those chronically sleep deprived, it may take a month or so until you fully recover those lost hours.

Catching Up On Sleep – How to Pay Back Your Sleep Debt

Catching up on sleep isn’t just a matter of sleeping in on the weekend. In fact, the late nights or interrupted sleep you’ve been experiencing this week may not seem like a big deal. You stay up late to finish a project, you have young children, you are a shift-worker or you just can’t stop binge-watching your favourite TV show.

We’ve all been there. But that extra hour or two of sleep that you skip each night could be doing you more harm than you think. And you may not even realise how sleep-deprived you are.

In fact, medical evidence suggests that for you to operate at your best, you need 7-9 hours of sleep each night. But if you’re like most people, you’re probably averaging 6-8 hours. Which means you have a huge sleep debt to repay. And it’s time to think about catching up on sleep.

What is Sleep Debt?

Sleep debt is the difference between the recommended amount of sleep you should get and the amount of sleep you actually get. So, if you have a big project due on Friday and you’ve been staying up late trying to finish it, by the end of the week you may have accumulated 5 hours of sleep debt.

Or, if you have young children who wake you in the middle of the night and you end up staying up for a few hours then you may accumulate a few hours sleep debt. Not too bad if it’s a one-off but if it’s happening every night then you need to start catching up on sleep.

How Do You Know If You Need To Catch Up On Sleep?

In some cases, sleep debt results from insomnia, a sleep disorder or other underlying conditions that may require medical attention. But most sleep debt is due to burning the candle at both ends.

And unless you’re actually keeping track of the nights when you don’t get enough sleep, you may not even realise how much sleep debt you have banked up. Not only that, but you may not realise how much that sleep debt is affecting your performance.

You may think you can function well on six hours of sleep each night, but the reality is that you’re not performing well at all. According to research conducted at the University of Pennsylvania School of Medicine, your sleep debt is actually affecting your normal cognitive abilities. What’s more, the research indicates, that you may be too sleep-deprived to even know how badly you’re performing.

“Routine nightly sleep for fewer than six hours results in cognitive performance deficits, even if we feel we have adapted to it,” says Hans P.A. Van Dongen, PhD, Assistant Professor of Sleep and Chronobiology in Penn’s Department of Psychiatry and author of the study.

“This work demonstrates the importance of sleep as a necessity for health and well-being. Even relatively moderate sleep restriction, if it is sustained night after night, can seriously impair our neurobiological functioning.”

If you know you’re not getting the recommended 7-9 hours sleep a night then start keeping track of it. Catching up on sleep is really important. Because while you may feel like you’re functioning fine on only 6 hours sleep, you could be performing a lot better.

Make a note of your sleep and wake times over a month and compare the total hours to the recommended sleep. You might be surprised how much sleep debt you have accumulated.

How Does Sleep Debt Affect Your Health?

You may think feeling a bit tired during the day isn’t a big deal. Or, you’ll feel better next week or next month. But the health consequences of not enough sleep each night can be debilitating.

After a healthy diet and exercise, sleep is the third pillar of health. But too often we see it as a luxury. Especially if you have small children, do shift work or have a stressful job.

You may think those sleepless nights are just a sacrifice you’re making for the short-term. But if you don’t start catching up on sleep you may be facing major health problems.

In fact, a recent study found that weekday sleep debt may lead to long-term metabolic disruption. Basically, sleep debt affects the way your body breaks down food and uses it to create energy. This may lead to or exacerbate type 2 diabetes.

The study included 522 patients and was conducted by Professor Shahrad Taheri, MBBS, PhD, professor of medicine at Weill Cornell Medical College in Qatar.

Professor Taheri found that compared with participants who had no weekday sleep debt, those who had weekday sleep debt were 72% more likely to be obese. And by the 6-month mark, weekday sleep debt was significantly associated with obesity and insulin resistance.

Not only that but lack of sleep long-term has been scientifically proven to lead to multiple health problems. For example, heart disease, stroke, depression, memory loss, infertility, and more. Catching up on sleep has never been more important for your health.

Can You Pay Back Your Sleep Debt?

The great news is that you can catch up on lost sleep and recover from your sleep debt. But it doesn’t happen in one go. If you’ve had a week of sleeping 6 hours each night, don’t expect a really good weekend sleep to make up for it.

Catching up on sleep needs to happen gradually. One hour or more additional sleep each night over a long period of time is the way to go.

5 Tips To Catch Up On Sleep

1. Go to bed when you are tired

Don’t try to push through. Start your bedtime routine earlier than usual and as soon as you feel tired go to bed.

2. Wake up naturally

Try not to use an alarm clock unless you absolutely have to. Wake up in your own time when your body is ready.

3. Be patient

Don’t expect to get 10 hours sleep on the first night you try to make up for your sleep debt. Be patient. It may take your body two weeks to make up for one week of late nights.

4. Bank it up

Try to bank up 10 hours of sleep per night if you can. Then, over time, when your body has fully recovered, you’ll find that you only need the recommended 7-9 hours sleep each night.

5. Practice healthy sleep hygiene

Even after you have recovered your sleep debt make good sleep hygiene part of your life. Check out our great tips for sleeping better.

Remember that sleep is the third pillar of health. Treat sleep with as much respect as you would diet and exercise.

Finally, if you think your sleep debt is related to a sleep disorder do something about it today. The negative consequences of sleep-disordered breathing are serious. Treatment is so easy and life-changing. Call us today on 1300 246 637 (or submit a confidential email using the form here) for a free no-obligation chat with one of our friendly Sleep Therapists. Contact us now.

Repaying your sleep debt

Why sleep is important to your health and how to repair sleep deprivation effects.

Updated: May 9, 2018Published: July, 2007

If sleep were a credit card company, many of us would be in deep trouble.

Medical evidence suggests that for optimum health and function, the average adult should get seven to nine hours of sleep daily. But more than 60% of women regularly fall short of that goal. Although each hour of lost slumber goes into the health debit column, we don’t get any monthly reminders that we’ve fallen in arrears.

In fact, the greater the sleep debt, the less capable we are of recognizing it: Once sleep deprivation — with its fuzzy-headedness, irritability, and fatigue — has us in its sway, we can hardly recall what it’s like to be fully rested. And as the sleep debt mounts, the health consequences increase, putting us at growing risk for weight gain, diabetes, heart disease, stroke, and memory loss.

In some cases, sleep debt results from insomnia or other underlying conditions that may require medical attention. But most sleep debt is due to burning the candle at both ends — consistently failing to get to bed on time and stay there until we’ve slept enough.

Fortunately, sleep doesn’t charge interest on the unpaid balance, or even demand a one-for-one repayment. It may take some work, but you can repay even a chronic, longstanding sleep debt.

How we sleep

We need sleep, and, in a sense, we’re programmed to be sure that we get it. The body summons sleep in two ways: by boosting circulating levels of the neurotransmitter adenosine and by sending signals from the circadian clock, which controls the body’s daily rhythms. Together, these two systems establish an ideal bedtime for each of us.

Adenosine is partly a by-product of the cells’ energy expenditure. As our cells produce power to move us through the day, adenosine is released into the bloodstream and taken up by receptors in the brain region that governs wakefulness (the basal forebrain). There, it acts like a dimmer switch, turning down many of the processes associated with wakefulness, such as attention, memory, and reactions to physical stimuli. As brain levels of adenosine mount, we feel drowsier. (Caffeine keeps us awake by blocking adenosine receptors in the brain.) When we sleep, our energy needs fall, and the level of circulating adenosine drops. After a good night’s sleep, the level is at its lowest, and we are most alert.

The circadian clock regulates all body functions — not just the pattern of sleeping and waking during the 24-hour cycle, but also fluctuations in body temperature, blood pressure, and levels of digestive enzymes and various hormones. Most of us experience a major “sleepiness” peak between 12 a.m. and 6 a.m. and a minor one between 2 p.m. and 4 p.m. Of course, individuals vary. The larks among us might be ready for bed at 9 or 10 p.m. and awake at 5 a.m., while some night owls don’t fall asleep until well after midnight and prefer sleeping until noon.

Advice for avoiding sleep deprivation

  • Create a sleep sanctuary. Reserve it for sleep, intimacy, and other restful activities, like pleasure reading and meditation. Keep it on the cool side. Banish the television, computer, Blackberry, and other diversions from that space.
  • Nap only if necessary. Night owls and shift workers are at the greatest risk for sleep debt. Napping an hour or two at the peak of sleepiness in the afternoon can help to supplement hours missed at night. But naps can also interfere with your ability to sleep at night and throw your sleep schedule into disarray.
  • Avoid caffeine after noon, and go light on alcohol.
  • Get regular exercise, but not within three hours of bedtime.
  • If you’re able to get enough sleep but don’t feel refreshed in the morning, discuss the problem with your clinician. Many common medical conditions, from depression to sleep apnea (the condition in which breathing pauses during sleep), could be responsible. If you’re finding it increasingly difficult to get enough sleep but don’t have an underlying medical problem, consider consulting one of the 1,100 sleep centers accredited by the American Academy of Sleep Medicine (www.sleepeducation.com).

Why we need sleep

Although sleep doesn’t trump food and water in the hierarchy of physical needs, we can’t live without it. Given the ethical limits on research involving human subjects, scientists have no direct evidence on how extended sleeplessness — that is, beyond a few days — affects human beings. Laboratory rats, however, have been deprived of sleep for long periods, and after a week or two, the results include loss of immune function and death from infections.

In a landmark study of human sleep deprivation, University of Chicago researchers followed a group of student volunteers who slept only four hours nightly for six consecutive days. The volunteers developed higher blood pressure and higher levels of the stress hormone cortisol, and they produced only half the usual number of antibodies to a flu vaccine. The sleep-deprived students also showed signs of insulin resistance — a condition that is the precursor of type 2 diabetes and metabolic slowdown. All the changes were reversed when the students made up the hours of sleep they had lost. The Chicago research helps to explain why chronic sleep debt raises the risk of obesity, heart disease, stroke, and diabetes.

Sleep loss exacts a toll on the mind as well as the body, as shown by a study done at the University of Pennsylvania and Harvard Medical School. The researchers studied 48 healthy men and women, ages 21 to 38, who had been averaging seven to eight hours of sleep nightly. They assigned three-quarters of the volunteers at random to three different groups that slept either eight, six, or four hours nightly; a fourth group agreed to go without sleep for three days. Every two hours during their waking periods, all the participants completed sleepiness evaluation questionnaires and took tests of reaction time, memory, and cognitive ability.

Over the course of two weeks, reaction times in the group that slept eight hours a night remained about the same, and their scores on the memory and cognitive tasks rose steadily. In contrast, scores for the four-hour and six-hour sleepers drew closer to those of the fourth group, whose scores had plummeted during their three days without sleep. After two weeks, the four-hour sleepers were cognitively in no better shape than the sleepless group after its first night awake. Their memory scores and reaction times were about on par with those of the sleepless after their second consecutive all-nighter. The six-hour sleepers performed adequately on the cognitive test but lost ground on reaction time and memory, logging scores that approximated those of the sleepless after their first night awake.

Meanwhile, the six-hour and the four-hour sleepers were failing to gauge reliably how sleepy they had become. At the end of the study, their self-rated sleepiness scores were leveling off, even as their performance scores continued to decline.

Selected resources

American Academy of Sleep Medicine www.aasmnet.org

American Sleep Apnea Association www.sleepapnea.org

Better Sleep Council www.bettersleep.org

National Sleep Foundation www.sleepfoundation.org

The architecture of the sleep cycle

Scientists have documented the debilitating effects of sleep deprivation very well, but they still know little about how sleep accomplishes its restorative handiwork. Since the earliest sleep studies, encephalography (EEG) has been used to trace the brain waves of volunteers as they slumber. EEG readings have revealed several distinct phases of sleep characterized by different brain-wave patterns. Information derived from subsequent sleep studies has enabled researchers to correlate brain activity with other physiological processes. Today, sleep laboratories are equipped to evaluate heart rate, blood pressure, oxygen levels, breathing, eye movement, muscle tension, and limb movement.

The studies show that there are two forms of sleep, distinguished by specific brain-wave activity and the presence or absence of rapid eye movement (REM). During non-REM sleep, brain waves become slower and more synchronized, and the eyes are still; during REM sleep, brain waves are faster and less organized, and the eyes scan back and forth under the lids.

We fall into non-REM sleep in four stages that represent a continuum of shallow to deep sleep. In Stage 1, characterized by relatively fast waves, we are perched on the brink of sleep and are readily aroused. By Stage 4, or slow-wave sleep, we are dead to the world; breathing has slowed considerably and blood pressure and heart rate have dropped by as much as 30%. The brain becomes less responsive to external stimuli, making it difficult to awaken. Although most of the body’s systems are in “sleep mode” at this stage, some are at their most productive. Early in Stage 4 sleep, for example, the pituitary releases a pulse of growth hormone that stimulates tissue growth and repair.

REM sleep sets the stage for dreams. Our eyes are scanning back and forth, but our skeletal muscles are paralyzed, perhaps to keep us from acting out our dreams. REM sleep also nurtures cognition and problem solving. Studies have shown that people learning a new physical task will improve their performance overnight, but only as long as they get sufficient REM sleep.

A typical night’s sleep consists of four or five REM/non-REM cycles with occasional, brief episodes of wakefulness. Most Stage 4 sleep occurs during the first two to three hours of sleep. As morning approaches, REM sleep occupies an increasing share of slumber.

Sleep cycles are mapped on what’s known as a hypnogram, a sort of bar graph for sleep stages (see illustration). Because the hypnogram looks like a city skyline, the sleep patterns that it records are dubbed “sleep architecture.” Like the urban landscape, sleep is reshaped over time. At age 20, we spend an average of 7.5 hours a night sleeping — with about 90 minutes each of REM and deep sleep — and we’re awake, intermittently, for about 18 minutes. By the time we’re 60, we’re only sleeping 6.2 hours a night. REM sleep has fallen to about 75 minutes; deep sleep to less than 40; and on a typical night, we’re awake for 44 minutes, on average. However, we don’t outgrow our need for sleep; it’s just harder to come by.

Sleep architecture

When experts chart sleep stages on a hypnogram, the different levels resemble a drawing of a city skyline. This pattern is known as sleep architecture. The hypnogram above shows a typical night’s sleep of a healthy young adult.

Countering the effects of sleep loss

Women often find it difficult to make up sleep lost while caring for infant children, juggling family and career, and weathering the perturbations of menopause. Even those who are fortunate enough to reach midlife fully rested may find themselves gradually slipping into the debit column after age 60.

Too often we regard sleep as an indulgence or luxury. Rather, we should recognize that adequate sleep is just as important for health as diet and exercise are. To that end, he offers the following advice:

  • Settle short-term debt. If you missed 10 hours of sleep over the course of a week, add three to four extra sleep hours on the weekend and an extra hour or two per night the following week until you have repaid the debt fully.
  • Address a long-term debt. If you’ve shorted yourself on sleep for decades, you won’t be required to put in a Rip Van Winkle–like effort to repay the hours of missed slumber. Nonetheless, it could take a few weeks to recoup your losses. Plan a vacation with a light schedule and few obligations — not a whirlwind tour of the museums of Europe or a daughter’s wedding. Then, turn off the alarm clock and just sleep every night until you awake naturally. At the beginning, you may be sleeping 12 hours or more a night; by the end, you’ll be getting about the amount you regularly need to awake refreshed.
  • Avoid backsliding into a new debt cycle. Once you’ve determined how much sleep you really need, factor it into your daily schedule. Try to go to bed and get up at the same time every day — at the very least, on weekdays. If need be, use weekends to make up for lost sleep. And don’t forget to follow the tried and true rules of sleep hygiene described above, in “Advice for avoiding sleep deprivation.”

As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

Can you make up for lost sleep?

We’ve all said it: “I’ll stay up late tonight and sleep late this weekend.” But can our bodies really catch up on sleep that we’ve lost? It seems logical to make up for lost Zs, but it doesn’t work exactly like this myth suggests.

We can make up for a portion of the hours we lost on the weekend but not all of it.

“Yes, people can make up for lost sleep on another day,” says Dr. Chuck Smith, one of our primary care physicians at UAMS. “The amount of sleep lost and recovered may not be the same, though. Most of the first few hours of sleep can be recovered, but if the amount of sleep lost is more than a few hours, not all of it will be recovered.”

Dr. Smith says that if you lose only five hours of sleep throughout the week, you can probably recover most of the five hours over the weekend. However, you may not recover all of the lost sleep if you lose over 20 hours.

Fortunately, even if you do lose a large amount of sleep throughout the week, Dr. Smith says that the body has its own recovery system that makes it easier for us to bounce back from a sleep deficit. And we may not even need to recover all the hours we failed to get.

“By nature our bodies try to recover as much of deep sleep and REM sleep that is lost and may forego other stages of sleep,” he says.

So how much sleep should we get each night? Generally, we need to have at least seven to eight hours of good quality sleep, Dr. Reddy says. And getting more or less than seven or eight hours a night can actually affect lifespan.

In order to get a good quality sleep, you must have “good sleep hygiene,” he says. Here are a few good sleep hygiene tips from Dr. Smith:

  • Have strict times for going to bed and waking up. “It can vary a little, but for the most part they should remain fairly consistent.”
  • Before going to bed, have a routine activity such as reading a book or listening to music.
  • Do not watch TV or play on the computer right before bedtime. “The bright light stimulates your brain so that you cannot fall asleep.”
  • Avoid caffeine after 3 p.m. and avoid excess caffeine in the morning.
  • Do not take naps. “If you really need a nap make sure it lasts no longer than 20 minutes.”

Can You Catch Up On Sleep?

Getty images

While yawns are indeed contagious, there’s another reason why Americans often seem so sleepy. A global survey found the U.S. has one of the highest rates of sleep deprivation, which makes us wonder: Can we catch up on those lost zzz’s?

Late to Bed, Early to Rise-Why It Matters

A good night’s rest is just as important as all that happens during daylight. An adequate amount of sleep allows the body to rest and recharge so we’re ready to tackle the day. It can also reduce stress and help us lose weight. Seven to nine hours of snoozing nightly should cut it, but studies show 35 percent of Americans don’t get enough sleep-clocking in less than seven hours nightly.

RELATED: Why Your Eye Twitches and How to Make it Stop

Between around-the-clock careers to late-night study sessions (procrastination, anyone?), there’s no shortage of reasons why people don’t sleep enough. But The Debt isn’t just a Hollywood thriller-sleep debt refers to the hours of sleep we should get minus the amount we actually get. Over time, sleep debt can add up, and the longer we go functioning on five hours of sleep (and maybe even downing a Four Loko or two), the harder it is to catch up on sleep. And no, sleeping for an entire weekend won’t cut it, even if those holiday office parties make us rather sluggish.

Hurry Up and Slow Down!-The Answer/Debate

After neglecting a night between the sheets (a.k.a. acute sleep deprivation), it’s possible to slowly repay sleep debt. (Student loans are another story.) An extra hour or two of sleep nightly is a foolproof remedy. But chronic sleep deprivation (defined as getting less than five hours of sleep per night over an extended time period) is harder to cure. In one study, people with acute sleep loss were focused and attentive after 10 hours of rest. Those with chronic sleep deprivation had problems staying alert even after the 10-hour snooze.

And research on chronic sleep deprivation is scary enough to jolt us without an espresso: The longer we go without getting enough sleep, the harder it is to realize we’re tired. After a while, those double frappuccinos won’t even be necessary-we won’t know we’re fatigued at all.

RELATED: How to Become a Morning Person

Since catching up on sleep becomes a tricky feat as our sleep debt accumulates, the best medicine for sleep loss is prevention. Forty-nine percent of Americans blame stress for losing sleep, so try taking some deep breaths and listening to music to calm the mind before bedtime. (Enya’s never a bad choice.) To help call it a night, read a book while sipping on some herbal tea, and squeeze in some exercise earlier in the day! These little tricks will help us avoid counting all those sheep in bed and will make failing to catch up on sleep a thing of the past.

The Takeaway

It’s possible to catch up on sleep if snoozing has slacked for a night or two. But the longer we go without catching enough Zzz’s, the harder it is to get ’em back.

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  • By Laura Schwecherl for Greatist.com

Catch up on lost sleep

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