Free tool

Sleep Debt Calculator: How Far Behind Are You This Week?

Your last seven nights against the sleep you need, and a realistic plan to repay the gap.

Hours you actually slept, last seven nights

-hours of sleep debt this week
-average hours per night
-nights under your need
-nights to clear it at your catch-up pace

What is sleep debt?

Sleep debt is the gap between the sleep you need and the sleep you get, added up night after night. Most adults need seven to nine hours; the American Academy of Sleep Medicine and the Sleep Research Society put the floor for adults at seven. Sleep an hour short on five nights and you are carrying five hours of debt, whether or not you feel it.

That last part is the problem. In the best-known laboratory study, healthy adults restricted to six hours a night for two weeks ended up performing like people who had been awake for two full nights, and their own sleepiness ratings barely moved. Sleep debt is quiet. The calculator above makes it visible.

How the calculator works

  • Need minus actual, every night. Each night under your need adds to the debt. Nights over your need count against it, because some recovery does happen when you sleep longer.
  • The repayment pace. Pick how many minutes you can realistically add per night. The calculator divides the debt by that amount. Thirty to sixty minutes earlier to bed is the pace most people can hold; a three hour lie-in on Sunday is not a pace, it is a one-off.
  • Why a single long night is not enough. After five nights of four hours' sleep, one ten hour recovery night restored only part of the lost performance in a dose-response study, and a Japanese laboratory study found that clearing about an hour of carried debt took several days of unrestricted sleep. Recovery is real but gradual.

How much sleep do you need?

Age Recommended per 24 hours
Teenagers, 14 to 17 8 to 10 hours
Adults, 18 to 64 7 to 9 hours
Adults, 65 and over 7 to 8 hours

These are the National Sleep Foundation consensus ranges. Within them, your own number is the amount after which you wake without an alarm on a free day and do not crash in the afternoon. A week of unrestricted sleep on holiday usually reveals it.

How to repay sleep debt

  1. Go to bed earlier, do not wake up later. A fixed wake time anchors your body clock. Moving bedtime earlier repays the debt without unsettling the clock; sleeping in on weekends shifts it, which is why Monday mornings feel like a short flight west.
  2. Add 30 to 60 minutes a night and hold it. That is the pace the calculator uses. Small and repeated beats large and occasional.
  3. Keep weekend changes under an hour. Researchers call the gap between weekday and weekend sleep timing social jet lag; the larger it is, the more tired people report feeling during the week.
  4. Nap short and early. Twenty to thirty minutes before 3 pm takes the edge off without eating into the night's sleep.
  5. Protect the evening from caffeine. An afternoon coffee quietly takes back the sleep you are trying to add. The caffeine cut-off calculator gives you a time.
  6. Get morning light. Ten minutes outside after waking makes the earlier bedtime easier to feel.

Sources

  1. Van Dongen HPA, Maislin G, Mullington JM, Dinges DF. The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. Sleep. 2003;26(2):117-126.
  2. 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.
  3. Kitamura S, Katayose Y, Nakazaki K, et al. Estimating individual optimal sleep duration and potential sleep debt. Scientific Reports. 2016;6:35812.
  4. Watson NF, Badr MS, Belenky G, et al. Recommended amount of sleep for a healthy adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. Sleep. 2015;38(6):843-844.
  5. Hirshkowitz M, Whiton K, Albert SM, et al. National Sleep Foundation's sleep time duration recommendations: methodology and results summary. Sleep Health. 2015;1(1):40-43.
  6. Wittmann M, Dinich J, Merrow M, Roenneberg T. Social jetlag: misalignment of biological and social time. Chronobiology International. 2006;23(1-2):497-509.

These studies looked at sleep restriction and recovery in general populations. None of them tested a Veluna product; this page relates to individual habits and is not the Veluna product.

Common questions

Can you catch up on sleep at the weekend?

Partly. Longer weekend sleep repays some of the week's debt, but laboratory studies show one long night restores only part of the lost performance, and sleeping in shifts your body clock later, which makes Monday harder. Earlier bedtimes on several nights work better than one long lie-in.

How long does it take to recover from sleep debt?

It depends on the size of the debt and the pace you repay it. Adding 30 to 60 minutes a night, a five hour debt clears in about a week. A debt built over months can take weeks of consistent extra sleep, and research suggests the recovery is gradual rather than a single catch-up night.

Is six hours of sleep enough?

For most adults, no. In a two-week laboratory study, people limited to six hours a night accumulated deficits in attention equal to two nights without sleep, while rating themselves only mildly sleepy. The joint American Academy of Sleep Medicine and Sleep Research Society statement recommends at least seven hours.

Does napping count toward sleep debt?

A short nap adds real sleep and helps alertness for the rest of the day. Keep it to 20 to 30 minutes and before mid-afternoon so it does not make the night's sleep harder to start.

What are the signs of sleep debt?

Needing an alarm every day, falling asleep within minutes of lying down, sleeping much longer on free days, afternoon crashes, more caffeine than usual, and feeling fine only to find concentration and mood slipping. The last one is the most common because the research shows people adapt to feeling tired without adapting to the deficit itself.

The repayment plan is an evening routineSleep debt is paid back at bedtime, not in the morning. A wind-down that starts at the same time every night is how the earlier bedtime actually happens.

Find your evening routine

This calculator is for general education and planning. It is not medical advice and does not diagnose, treat, cure or prevent any condition. Talk to a healthcare professional about your own situation, especially if you are pregnant, nursing, take medication or have a medical condition.