Sleep calculator
Tell us when you have to be up, and we'll tell you when to sleep so the alarm catches you between sleep cycles, not in the middle of one.
Adjust for how you sleep
Most adults fall asleep in 10 to 20 minutes. If you wake up groggy even at the suggested times, try an 85 or 95 minute cycle for a week.
Why the time you wake up matters as much as how long you sleep
Your night isn't one long block of rest. It's a series of cycles, each lasting about 90 minutes. In every cycle you drift into light sleep, sink into deep sleep, then rise into REM sleep, where most dreaming happens. At the end of each cycle you come close to waking for a moment, usually without remembering it.
If your alarm rings during deep sleep, you get sleep inertia: heavy eyelids, a slow brain and the urge to hit snooze. If it rings at the end of a cycle, getting up feels far easier, even when you've slept a little less.
How we work out your times
- We start from your wake-up time (or your bedtime).
- We count back or forward in full cycles of 90 minutes: 3, 4, 5 and 6 cycles.
- We add 15 minutes for falling asleep. You can change this, and the cycle length, under "Adjust for how you sleep".
- We show you the full night as a chart, so you can see when deep sleep and REM roughly happen.
Five cycles (7.5 hours) is the sweet spot for most adults. Six cycles (9 hours) suits teenagers and anyone paying back lost sleep. Four cycles is a short night that most people can handle once in a while.
Bedtime chart for common wake-up times
Times already include 15 minutes to fall asleep. Tap a wake-up time for a full page with more options.
| Wake up at | Bed at, for 9 h (6 cycles) | Bed at, for 7.5 h (5 cycles) | Bed at, for 6 h (4 cycles) |
|---|---|---|---|
| 4:30 AM | 7:15 PM | 8:45 PM | 10:15 PM |
| 5:00 AM | 7:45 PM | 9:15 PM | 10:45 PM |
| 5:30 AM | 8:15 PM | 9:45 PM | 11:15 PM |
| 6:00 AM | 8:45 PM | 10:15 PM | 11:45 PM |
| 6:30 AM | 9:15 PM | 10:45 PM | 12:15 AM |
| 7:00 AM | 9:45 PM | 11:15 PM | 12:45 AM |
| 7:30 AM | 10:15 PM | 11:45 PM | 1:15 AM |
| 8:00 AM | 10:45 PM | 12:15 AM | 1:45 AM |
Going to bed at a set time instead? See wake-up times for every bedtime.
India's sleep, by the numbers
Indians sleep later than almost anyone else in Asia, and the habit is getting worse, not better. Here's what recent surveys found.
of Indians said they got less than 6 hours of uninterrupted sleep a night, up from 50% in 2022.
LocalCircles survey, via The Tribune, 2024use their phone right before bed, the most common sleep-wrecking habit in urban India.
Great Indian Sleep Scorecard 2026of urban Indians go to bed before 10 PM. Nearly 60% sleep after 11 PM.
Great Indian Sleep Scorecard 2026Surveys are self-reported and lean towards urban, online respondents, so treat these as signals rather than exact national figures.
Sleep timing for real Indian routines
A sleep plan only works if it fits your actual day. Here are worked examples. Tap one to load it into the calculator.
School student, 6:45 AM bus
Wake 6:00 AM, lights out 10:15 PM
Teenagers need 8 to 10 hours. Six cycles is ideal, five is the floor on school nights. Homework and phones are the usual reason this slips.
Plan for a 6:00 AM alarmOffice commuter, 7:50 local train
Wake 6:30 AM, lights out 10:45 PM
Long commutes in Mumbai, Delhi NCR and Bengaluru eat into the night. Protect your bedtime by having dinner before 9 PM, not after.
Plan for a 6:30 AM alarmNight shift, 7 PM to 4 AM
Home 5:00 AM, sleep 5:45 AM to 1:30 PM
BPO, IT support, hospital and factory staff need a fixed daytime sleep block, blackout curtains, and a firm caffeine cut-off.
Plan your shift sleepBoard exams or NEET and JEE prep
Wake 6:00 AM, lights out 10:15 PM
Memory is filed away during deep and REM sleep. An all-nighter before a paper costs more marks than the extra revision earns.
Read the student guideSehri during Ramzan
Wake 4:15 AM, lights out 10:00 PM
Four cycles after Isha, then a 20 minute nap in the afternoon to cover the gap. Keep sehri light so you can fall back asleep if needed.
Plan for a 4:15 AM alarmBrahma Muhurta riser
Wake around 4:30 AM, lights out 8:45 PM
The traditional pre-dawn hour shifts with sunrise through the year. Get today's exact time for your city.
Find today's Brahma MuhurtaWhat happens inside one sleep cycle
Each cycle runs through four stages. The mix changes as the night goes on: deep sleep is concentrated in the first two or three cycles, while REM stretches longer towards morning. That's why cutting the end of the night short costs you mostly REM, the stage linked to mood and memory.
| Stage | What's happening | Share of the night |
|---|---|---|
| N1, light sleep | The doorway into sleep. Muscles relax and you can be woken easily. | About 5% |
| N2, core sleep | Heart rate and temperature drop. The brain sorts the day's information. | About 45 to 55% |
| N3, deep sleep | Growth hormone is released and the body repairs itself. Hardest stage to wake from. | About 15 to 25% |
| REM sleep | Vivid dreams, busy brain, relaxed muscles. Important for memory and emotions. | About 20 to 25% |
More sleep tools
Questions people ask
What time should I sleep if I wake up at 6 AM?
To wake up at 6:00 AM between sleep cycles, fall asleep at 10:30 PM (5 cycles, 7.5 hours) or 9:00 PM (6 cycles, 9 hours). If you take about 15 minutes to drift off, switch off the lights at 10:15 PM or 8:45 PM. A shorter option is 12:00 AM, which gives 4 cycles (6 hours) and is fine for an occasional night.
How does a sleep calculator work?
Sleep comes in cycles of roughly 90 minutes. Each cycle moves from light sleep into deep sleep and then into REM sleep before you surface briefly. A sleep calculator counts back (or forward) in whole cycles from your alarm and adds the time you take to fall asleep, so the alarm rings at the end of a cycle instead of in the middle of deep sleep.
Why do I feel tired after 8 hours of sleep but fresh after 6?
It is often about where in the cycle your alarm catches you. Waking from deep sleep causes sleep inertia, the heavy, confused feeling that can last 15 to 30 minutes. Six hours is exactly four cycles, so you may surface naturally, while eight hours can land you in deep sleep. That said, six hours is not enough for most adults over the long run, so aim for 7.5 hours timed well.
Is 90 minutes the same for everyone?
No. Ninety minutes is an average. Individual cycles can run anywhere from about 70 to 120 minutes and change through the night. Use the settings to try 85 or 95 minutes if the default times don't suit you, and stick with one setting for a week before judging it.
What is the best time to sleep in India?
For most working adults and students in India who wake between 6 and 7 AM, falling asleep between 10:30 and 11:30 PM gives 7.5 hours of sleep. Later dinners and long commutes push many people past midnight, which is fine only if you can also wake later. A consistent time matters more than an early one.
How many sleep cycles do I need?
Most adults need 5 cycles (7.5 hours). Some feel best with 6 cycles (9 hours), especially teenagers and people recovering from a hard week. Four cycles (6 hours) is a short night. Three cycles (4.5 hours) should be an emergency, not a habit.
Does the calculator use Indian Standard Time?
The calculator uses whatever clock time you enter, so it works in any time zone. The 'Going to bed now' button reads the time on your phone or computer, which is IST for anyone in India.
Can I use this to plan a nap?
Naps work differently because you usually want to avoid deep sleep altogether. Use the nap calculator for a 20 minute power nap or a full 90 minute cycle.