One sleepless night is worth about 134 calories#
Staying awake does cost more than sleeping, and the price has been measured rather than modelled. Seven healthy adults, mean age 22, spent three days sealed inside a whole-room indirect calorimeter. The first 24 hours were baseline: 16 hours awake, 8 hours asleep. Then came 40 hours of continuous wakefulness, followed by 8 hours of recovery sleep. Across the first 24 hours of sleep deprivation, total energy expenditure rose about 7% — roughly 134 ± 2.1 kcal — against the baseline day1.
That is the entire prize for a completely sleepless night: about a tablespoon of olive oil. And it is the gross figure, before the accounting that makes up the rest of this article. If you arrived wondering whether a late night quietly works in your favour, the answer is that it works in your favour by roughly the width of a rounding error, and against you by considerably more — the intake side is laid out in how much more you eat after a bad night's sleep. The related and more common question, whether short sleep slows your metabolism, is settled separately in does poor sleep slow your metabolism; this page is about the opposite direction, and about why a real increase in burn still ends up meaning nothing.
One design detail makes Jung's number unusually clean. Participants were kept on bed rest for the entire protocol. They were not pacing, snacking, doing laundry or going to the gym at 2am. So 134 kcal is close to the pure cost of being conscious for eight hours that should have been sleep — not the cost of doing anything with them.
Sleep is not a shutdown. It is about a 5% discount.#
The reason the prize is so small is that the thing you are skipping was never expensive. Sleep gets described as the body powering down, which implies there is a lot of power to recover by staying up. There isn't.
Whole-body calorimetry across 80 healthy subjects, measured on 246 separate occasions, put a ratio on it. In a subgroup of 40 lean adults, the mean ratio of overnight metabolic rate to basal metabolic rate was 0.95 — sleep running about 5% below the resting baseline. Even the lowest sleeping metabolic rate reached during the night averaged 0.88 of BMR, a 12% discount at the deepest point2. The authors' practical conclusion was that using BMR to estimate overnight expenditure overestimates it by roughly 5% during actual sleep hours, and that over a full 24 hours the error becomes negligible.
A 5% discount is not a hibernation. Your organs keep working through the night at nearly the same rate they work at while you lie awake, which is the same reason resting expenditure is so hard to move in either direction. Jung's data agrees from the other side: differences in expenditure between sleep stages were small, and the thing that raised expenditure during a sleep episode was simply being awake within it.
Run the arithmetic on Jung's night-time figure and the hourly rate falls out. Expenditure across the 8-hour night was about 32% higher — roughly 161 kcal — on the sleepless night. A 32% increase of 161 kcal implies a baseline night of about 503 kcal, so roughly 63 kcal per hour asleep against about 83 kcal per hour awake in bed. That division is ours, not the paper's, but it puts a number on the trade: an extra hour of consciousness is worth about 20 calories.
The part nobody quotes: your body takes most of it back#
Here is the finding that changes the answer, and it sits in the same paper as the headline everyone repeats.
During the recovery period — the final 16 waking hours plus 8 hours of recovery sleep — 24-hour energy expenditure fell about 5% below baseline, roughly 96 ± 25 kcal. The recovery night alone ran about 4% below the baseline night, some 28 kcal cheaper1. The authors read this as evidence that human metabolic physiology can adjust to the energetic cost of lost sleep.
| Window | Change vs baseline | Approximate kcal |
|---|---|---|
| The sleepless night itself (8 h) | +32% | +161 |
| First full 24 h of deprivation | +7% | +134 |
| The recovery night (8 h asleep) | −4% | −28 |
| The full recovery 24 h | −5% | −96 |
Read the top two rows against each other before the bottom two. The night alone ran 161 kcal above baseline, yet the 24 hours containing it came in at only 134. The daytime that followed the sleepless night therefore ran below baseline — the economising starts immediately, before any recovery sleep happens at all. That inference is ours from the two published figures rather than a claim the paper makes, but it is hard to read the numbers any other way.
Gross, one sleepless night costs 134 calories. Net of what the body reclaims over the following day, it costs about 38. The debt is settled quietly, and not in your favour.
That subtraction deserves its caveats stated as plainly as the result. The two figures come from different 24-hour windows rather than a single balance sheet, and their precision is wildly unequal — ±2.1 kcal on the deprivation estimate against ±25 on the recovery one. Seven people is seven people. So treat 38 kcal as an order of magnitude, not a measurement. The direction, though, is unambiguous, and the direction is what matters: whatever you win by staying up, a chunk of it is repossessed while you sleep it off.
A short night is not a small all-nighter#
Everything above describes total sleep deprivation, which is not what most people are actually doing. The realistic exposure is a run of short nights — and there the expenditure signal gets weaker rather than merely smaller.
Nine healthy men were run through a randomised crossover of three consecutive nights at 3.5 hours in bed versus three at 7 hours, measured in a whole-room calorimeter. Total daily energy expenditure was 3,741 ± 303 kcal/day on the short-sleep condition against 3,717 ± 288 on the long — a difference of 24 kcal and a p-value of 0.5083. Statistically, nothing. Their 48-hour mean core body temperature actually fell slightly on short sleep, 36.68°C against 36.75°C.
A five-night study at 5 hours in bed did find expenditure up about 5%, and it is the number the cluster's metabolism article works through in detail4. Set that beside Hibi's null and the pattern across all three is coherent rather than contradictory: the more waking hours you add, the more clearly the extra burn shows up, and every one of these effects is small enough that a study of nine or sixteen people can easily fail to resolve it. Nobody has found the effect running the other way.
What Hibi's participants did show was on the intake side. After three short nights, fasting peptide YY — a satiety hormone — fell significantly, fullness ratings dropped, and hunger and prospective food consumption both rose. Same expenditure, hungrier people. That is the whole topic in one crossover.
Why gross calorie math misleads here#
This is a small, clean example of a mistake that shows up everywhere in calorie thinking: pricing one side of a transaction and calling it the result.
The gross figure is real. Twenty calories an hour is a genuine, replicated, physiologically sensible number. It is also, on its own, useless — because the same hours that generate it are hours in which a kitchen is available, judgement is degraded, and appetite regulation is measurably shifted. The extra burn is metabolically automatic; the extra eating is behaviourally near-automatic and roughly an order of magnitude larger. In Markwald's protocol, participants burning more still gained 0.82 ± 0.47 kg across five days.
So the useful framing is not "does staying up burn calories" — it does — but "what does the whole night cost." Three items land on that ledger: about +134 kcal of burn, minus about 96 kcal your body reclaims, plus several hundred kcal of intake you did not plan on. Only one of those three is big enough to see on a scale, and it is not the one in the headline. Caffeine has the same shape of answer, incidentally, and the same gap between a measurable effect and a useful one.
The reasonable conclusion is unglamorous. Sleep is not a metabolic luxury you are paying for in calories; it is close to free, costs about 5% of your resting rate, and the hours you take back from it are the most expensive hours in your day for reasons that have nothing to do with expenditure. The full case for treating sleep as a weight-management variable is the pillar.
FAQ#
Do you get the extra calories back when you catch up on sleep?#
Most of them, in the one study that measured it. After 40 hours of wakefulness, participants' 24-hour energy expenditure during the recovery period ran about 5% below baseline — roughly 96 ± 25 kcal — with the recovery night itself about 4% cheaper than a normal night1. Against a gross cost of about 134 kcal, that leaves something in the region of 38 kcal, though the subtraction is ours and the recovery estimate is far less precise than the deprivation one.
Is losing sleep a way to lose weight?#
No, and the arithmetic is not close. The gross gain is about 20 kcal per extra waking hour, partly reclaimed afterwards, while short sleep reliably raises hunger and lowers satiety signalling — fasting peptide YY fell and hunger rose after just three short nights3. In a five-day restriction study people burned more and still gained 0.82 kg4.
Why does a short night burn fewer extra calories than an all-nighter?#
Because the only thing generating the extra burn is waking hours, and a short night adds few of them. A full all-nighter converts eight cheap sleeping hours into expensive waking ones and lifts 24-hour expenditure about 7%1; three nights at 3.5 hours produced no detectable change in total expenditure at all3. Since sleep runs only about 5% below basal rate to begin with2, there is not much to reclaim per hour.
Sources#
- Jung CM, Melanson EL, Frydendall EJ, Perreault L, Eckel RH, Wright KP. Energy expenditure during sleep, sleep deprivation and sleep following sleep deprivation in adult humans. J Physiol. 2011;589(Pt 1):235-244.
- Goldberg GR, Prentice AM, Davies HL, Murgatroyd PR. Overnight and basal metabolic rates in men and women. Eur J Clin Nutr. 1988;42(2):137-144.
- Hibi M, Kubota C, Mizuno T, et al. Effect of shortened sleep on energy expenditure, core body temperature, and appetite: a human randomised crossover trial. Sci Rep. 2017;7:39640.
- Markwald RR, Melanson EL, Smith MR, et al. Impact of insufficient sleep on total daily energy expenditure, food intake, and weight gain. Proc Natl Acad Sci U S A. 2013;110(14):5695-5700.
