Sleep, stress and hunger
"I sleep five hours and I'm hungry all the time. Are those connected?" Yes, and it has been measured.
What the trials show
A systematic review and meta-analysis of controlled sleep-restriction studies found that after partial sleep deprivation people ate on average about 385 kilocalories more the next day than after normal sleep — with no matching increase in what they used. The studies are short laboratory protocols, one to fourteen nights, so they show the mechanism cleanly and say less about what happens over a year; the long-term association between short sleep and higher weight comes from observational data, with the usual caveats. But the direction is not in doubt, and the size is enough to erase a typical deficit.
Why: appetite, not metabolism
The extra intake did not come from a slowed metabolism; energy expenditure was essentially unchanged in the same studies. It came from appetite and from food choice — more snacking, more energy-dense food, more eating late. Tired people are hungrier and reach for different things. That is the whole mechanism this page needs; the hormonal details (the ghrelin and leptin figures that circulate) are context, not an explanation you have to act on.
Stress
Stress works through the same door. For many people the reliable response to a hard day is eating for comfort — quickly, at night, foods that are pleasant and dense. That is a learned response to a real need, not a character flaw, and the useful question is not "how do I stop it" but "what else meets that need on a Tuesday night". Sleep is often part of the answer here too: stress shortens sleep, and short sleep raises the appetite that stress then points at.
What makes a difference
- Sleep is an input to the energy model, not an excuse. The app's daily target is built from the sleep you actually had; the weekly estimate assumes a usual night, and a run of short ones changes the target.
- A smaller deficit in a bad week beats a large one that fails. If a stretch of poor sleep or high stress is coming — a deadline, a newborn, exams — plan maintenance or a gentle deficit for it, on purpose, and resume afterwards.
- Protein and volume are the same levers as on the hunger page, and they work on tired hunger too.
- Protect the last hour. Most sleep-related eating happens late; a planned evening snack, logged, beats an unplanned one.
When it is a medical question
Chronic insomnia, loud snoring with daytime exhaustion, or sleep that never refreshes can be conditions in their own right — apnoea among them — and a doctor, not a diet, is the first step.
In the app
Sleep is a required input in Energy Setup and in the daily context; a night of five hours recomputes that day's target, not the whole week, and nothing about the change is a judgement.