Can Intermittent Fasting Cause Insomnia? How to Fast Without Losing Sleep
By WellnessVigor · Updated October 10, 2026 · 7 min read
Intermittent fasting (IF) is one of the most popular ways to lose weight. Some people say it helps them sleep better; others find themselves lying awake hungry or waking in the night.
Here is what research says about intermittent fasting and sleep, why some people struggle, and how to set up your eating window so you can sleep well.
Quick answer
For most people, intermittent fasting does not seriously harm sleep, and research overall shows little effect on sleep quality. But some people get insomnia, especially in the first weeks, if they go to bed hungry, eat a huge meal right before bed, drink more coffee to get through fasting, or use very long fasts. Ending your eating window 2 to 3 hours before bed with a balanced meal usually helps.
Studies of time-restricted eating, such as 16:8 or 14:10 schedules, generally show little or no harm to sleep quality or duration for most healthy adults, though results vary and many studies are small. Research on religious fasting such as Ramadan, where eating and sleep times shift sharply, shows more sleep disruption, which suggests that meal timing relative to sleep matters.
Why intermittent fasting can disturb sleep
- Hunger at bedtime. If your eating window ends at 2 p.m. and you sleep at 11 p.m., hunger may keep you awake. See why you wake up hungry at night.
- Big meals close to bed. Cramming a day of food into a late window can cause reflux and broken sleep. See is it bad to sleep right after eating?
- More caffeine. Coffee and tea are often used to get through the fast and can linger in the body for hours.
- Too few calories overall. A very large deficit can act as a stressor. See why dieting can disturb sleep.
- Adjustment period. Many people sleep worse in the first 1 to 2 weeks, then adapt.
How to fast and still sleep well
- Choose a sleep-friendly window. For a typical 11 p.m. bedtime, an eating window of about 10 a.m. to 6 p.m. or 11 a.m. to 7 p.m. works well for many people.
- Finish eating 2 to 3 hours before bed.
- Make the last meal balanced and filling: protein, vegetables, complex carbs and some healthy fat.
- Get enough protein across your meals. See how much protein you need.
- Limit caffeine to the morning.
- Start gently with a 12-hour overnight fast before moving to 14:10 or 16:8.
- Be flexible. If you are often hungry at night, widen your window or end it a little later.
Sleep is the foundation of any diet. The 14-Day Sleep Reset helps you sleep deeply while you work towards your weight goals.
Who should be careful with fasting
Talk to a doctor before fasting if you have diabetes (especially on insulin or medicines that lower blood sugar), are pregnant or breastfeeding, have a history of an eating disorder, take medicines that must be taken with food, or are under 18.
Keep reading
Frequently asked questions
Does intermittent fasting affect sleep?
What is the best intermittent fasting schedule for sleep?
Can I drink tea at night while fasting?
Why do I wake up at night when fasting?
Sources
This article is for general information only and is not medical advice. See our Medical Disclaimer.