Sleep Calculator
Find the best time to go to bed or wake up based on 90-minute sleep cycles, so you wake up refreshed instead of groggy. Pick a time, or tap Sleep now.
How the sleep calculator works
While you sleep, your body moves through repeating sleep cycles of about 90 minutes — from light sleep, into deep sleep, and then into REM (dream) sleep. A full night is usually 5 to 6 complete cycles (7.5 to 9 hours). The trick to waking up refreshed is to wake at the end of a cycle, during light sleep, rather than being jolted awake mid-cycle when you feel groggy.
This calculator counts in 90-minute blocks from your chosen time and adds about 15 minutes to fall asleep:
Bedtime = wake time − (cycles × 90 min) − 15 min to fall asleep
Wake time = bedtime + 15 min + (cycles × 90 min)
It's a helpful guide, not a strict rule — real cycles vary a little from person to person and night to night. Use it alongside how you actually feel when you wake.
Need a quick recharge instead of a full night? For a power nap, aim for about 20 minutes — short enough to avoid deep sleep — or a full 90-minute cycle if you have time; both leave you clearer than a groggy 45-minute nap. The same cycle logic helps night-shift workers and anyone beating jet lag: pick a realistic sleep window and count in 90-minute cycles, whether you want to wake at 5 AM, 6 AM or 7 AM.
The bigger secret: a regular schedule
Here's something most sleep calculators miss. Recent research suggests that sleep regularity — going to bed and waking at consistent times — can predict long-term health even more strongly than the total number of hours you sleep. A steady rhythm keeps your body clock (circadian rhythm) aligned, which supports everything from mood to metabolism. So the single best upgrade for most people isn't a perfect number of hours — it's a consistent bedtime and wake time, even on weekends.
How much sleep do you need?
| Age group | Recommended sleep |
|---|---|
| Newborns & babies (0–1 yr) | 12–17 hours |
| Children (1–12 yrs) | 9–14 hours |
| Teenagers (13–18) | 8–10 hours |
| Adults (18–64) | 7–9 hours |
| Older adults (65+) | 7–8 hours |
Based on CDC / National Sleep Foundation guidance. Individual needs vary.
Foods & habits that help you sleep
A few evidence-backed nudges can make falling asleep easier:
| Helpful foods | Helpful habits |
|---|---|
| Tart cherries / cherry juice (melatonin) | Keep a consistent bed & wake time |
| Kiwi (serotonin) | Cool, dark, quiet bedroom |
| Almonds & walnuts (magnesium) | No caffeine 6–8 hours before bed |
| Fatty fish, bananas, warm milk (tryptophan) | No screens for an hour before bed; get morning sunlight |
Sleep matters worldwide — surveys suggest nearly half of adults in India, and over half of people globally, regularly fall short on sleep. Small, steady changes add up. This is general information, not medical advice.
🦉 Bonus: What's your sleep type? (chronotype quiz)
Are you a morning lark, a night owl, or somewhere in between? Answer 5 quick questions — your chronotype shapes your ideal bedtime.
Frequently asked questions
What time should I go to bed to wake up feeling refreshed?
Count back from your wake time in 90-minute cycles and add ~15 minutes to fall asleep. Aim for 5–6 cycles (7.5–9 h). To wake at 6:30 AM, go to bed by about 9:15 PM (6 cycles) or 10:45 PM (5 cycles).
How does the sleep cycle calculator work?
Sleep runs in ~90-minute cycles (5–6 a night). The tool counts back or forward in 90-minute blocks and adds ~15 minutes to fall asleep, so you wake at the light end of a cycle rather than mid-cycle when you feel groggy.
How many hours of sleep do I need?
Adults: 7+ hours; teens (13–18): 8–10; children (6–12): 9–12; younger children more; 65+: 7–8. Needs vary by person.
Is it better to wake up at the end of a sleep cycle?
Yes — waking during light sleep at a cycle's end feels more refreshing than waking mid deep-sleep, which leaves you groggy. It's a guide, not a guarantee.
Does a regular sleep schedule matter more than total hours?
Recent research suggests sleep regularity can predict long-term health even more strongly than total hours. A steady bed/wake time — even on weekends — is one of the most powerful habits.
What foods and habits help you sleep better?
Tart cherries (melatonin), kiwi, almonds/walnuts (magnesium), fatty fish, bananas, warm milk (tryptophan). Habits: consistent schedule, cool dark room, no caffeine 6–8 h before bed, limit alcohol, no screens an hour before bed, morning sunlight.
What time should I go to bed to wake up at 5 AM?
Go to bed by about 7:45 PM (6 cycles / 9 h) or 9:15 PM (5 cycles / 7.5 h), allowing ~15 minutes to fall asleep. Enter 5:00 AM above for exact times.
How long should a power nap be?
About 20 minutes keeps you in light sleep so you wake alert. A full 90-minute cycle also works; avoid ~45–60 minute naps that leave you groggy.