Yes. Sleeping hours count toward an everyday intermittent-fasting window. The window begins after your last calorie-containing food or drink and ends when you next consume calories. You do not start counting when you fall asleep or stop when you wake up. Time spent sleeping is part of the same continuous interval.[1][2]
For example, if you finish dinner at 7 p.m. and eat breakfast at 7 a.m., you have gone 12 hours without calories. The hours before bed, during sleep, and after waking all count.
Table of Contents
How do you count fasting hours while sleeping?
- Note when you finished your last calorie-containing food or drink.
- Count the hours that pass, including sleep.
- Stop counting when you next have calories.
| Last calories | Next calories | Time without calories |
|---|---|---|
| 8 p.m. | 8 a.m. | 12 hours |
| 7 p.m. | 9 a.m. | 14 hours |
| 8 p.m. | Noon | 16 hours |
These are arithmetic examples, not targets you need to reach. A 16-hour window does not become more effective just because more of it was spent asleep, and a longer fast is not automatically better for everyone.[2][3]
Does the fast start at bedtime or end when you wake up?
Neither. If dinner ends at 7 p.m. and you go to bed at 11 p.m., the four hours before bed are already part of your fasting window. If you wake at 7 a.m. but do not eat until 9 a.m., those two waking hours count too. The timing of food and drinks with calories determines the window; sleep and waking do not reset it.[1][2]
This also means sleeping through most of a planned fasting window is not “cheating.” Those hours count once, just like waking hours. Sleep does not add bonus fasting time or guarantee a particular health result.[2][3]
What if you eat or drink something during the night?
For a calorie-free intermittent-fasting window, a midnight snack or calorie-containing drink ends the window you were counting. If you then begin another stretch without calories, count that new stretch from your last calorie-containing intake. For example, dinner at 7 p.m., a snack at midnight, and breakfast at 8 a.m. makes two separate intervals: five hours and eight hours, not one 13-hour uninterrupted fast.[2]
Water and zero-calorie drinks such as black coffee or plain tea can fit an everyday intermittent-fasting routine.[2] Milk or cream in coffee, juice, sweetened drinks, alcohol, and calorie-containing broth need to be counted as intake under a calorie-free rule. For more food and drink examples, see what breaks an intermittent fast and what you can drink during intermittent fasting.
Do naps count? Is an overnight fast enough?
A nap counts if it occurs during an existing period without calories. It does not start a new fast or add extra hours. Likewise, a 12-hour overnight interval counts as 12 hours without calories; whether that schedule suits your goals and health is a separate question.
Choose a routine that lets you sleep and eat adequately. Extending a fast at the expense of sleep, medication timing, or your ability to function is not a goal in itself. Intermittent fasting is not appropriate for everyone, and its long-term effects and the relative benefits of different schedules remain uncertain.[2][3]
Bottom line
For everyday intermittent fasting, count from your last calories to your next calories. Include the hours you sleep, but do not add them twice. Bedtime and waking do not reset the clock; calorie-containing intake does.
Medical disclaimer
This article is general education, not medical advice. Medical tests, procedures, medications, and religious fasts may follow different rules; use the instructions that apply to your situation. Speak with a qualified healthcare professional before trying intermittent fasting if you have a medical condition, take medication that may be affected by meal timing, are pregnant or breastfeeding, are under 18, have diabetes or blood-sugar concerns, have a history of an eating disorder, or develop concerning symptoms.[2][3]
References
- UMass Memorial Health. Intermittent Fasting — Does It Deliver on Its Promise? Accessed November 3, 2026.
- Johns Hopkins Medicine. Intermittent Fasting: What Is It, And How Does It Work? Updated April 7, 2026. Accessed November 3, 2026.
- Mayo Clinic. Intermittent fasting: What are the benefits? March 8, 2025. Accessed November 3, 2026.