Sleep calculator: when to go to bed and wake up

The short answer

Count back 7 to 9 hours of sleep plus about 15 minutes to fall asleep from the time you need to wake up. For a 7:00 a.m. alarm that means lights out between about 9:45 and 11:45 p.m. If your bedtime is much later now, move it 15 minutes earlier every few days instead of all at once.

Bedtime chart for common wake-up times

Lights-out times below include 15 minutes to fall asleep. Pick the column that matches how much sleep you usually need.

Wake up	7 hours	7.5 hours	8 hours	9 hours
5:00 a.m.	9:45 p.m.	9:15 p.m.	8:45 p.m.	7:45 p.m.
5:30 a.m.	10:15 p.m.	9:45 p.m.	9:15 p.m.	8:15 p.m.
6:00 a.m.	10:45 p.m.	10:15 p.m.	9:45 p.m.	8:45 p.m.
6:30 a.m.	11:15 p.m.	10:45 p.m.	10:15 p.m.	9:15 p.m.
7:00 a.m.	11:45 p.m.	11:15 p.m.	10:45 p.m.	9:45 p.m.
7:30 a.m.	12:15 a.m.	11:45 p.m.	11:15 p.m.	10:15 p.m.
8:00 a.m.	12:45 a.m.	12:15 a.m.	11:45 p.m.	10:45 p.m.

How much sleep do adults need?

Age	Recommended	Source
18 to 64	7 to 9 hours	National Sleep Foundation (2015)
65 and older	7 to 8 hours	National Sleep Foundation (2015)
All adults	7 hours or more on a regular basis	AASM and Sleep Research Society (2015)

Why the calculator puts hours before sleep cycles

You will often read that you should wake at the end of a 90-minute sleep cycle. Cycles do average about 90 minutes, but they vary between people and change through the night, so an exact cycle count is a rough guide at best. The calculator shows cycles for reference and bases each option on total hours, which is what the sleep recommendations above are written in.

How to make a new bedtime stick

1. Fix the wake-up time first. A steady wake-up time, weekends included, anchors the rest of the schedule.
2. Get daylight soon after waking. Morning light helps move your body clock earlier; bright evening light pushes it later.
3. Start a wind-down alarm. Set an alarm 30 to 60 minutes before lights out to start your bedtime routine.
4. Shift in small steps. Use the shift planner above rather than moving an hour at once.

More help: what time should I go to bed, how to fix your sleep schedule and the personal 30-day evening routine plan. If you snore loudly, stop breathing during sleep or feel very sleepy in the day, talk to a doctor.

Frequently asked questions

How much sleep do adults need?

Sleep experts recommend at least 7 hours a night for adults, with 7 to 9 hours for ages 18 to 64 and 7 to 8 hours from 65. Some people need a little more or less; how you feel during the day is a useful check.

What about 90-minute sleep cycles?

Sleep cycles average about 90 minutes but vary from roughly 70 to 120 minutes between people and through the night. That is why the calculator shows cycles as a guide and puts total hours first.

How long does it take to fall asleep?

Many healthy adults fall asleep in about 10 to 20 minutes. The calculator adds 15 minutes by default; change it if you know you usually take longer.

How can I go to bed earlier?

Move your bedtime and wake-up time 15 minutes earlier every few days, get daylight soon after waking and dim screens and lights in the last hour. The shift planner below turns that into a dated schedule.

Is this medical advice?

No. It is a planning tool for healthy adults. If you snore loudly, stop breathing in your sleep, feel very sleepy during the day or cannot sleep most nights, talk to a doctor.

Sources and evidence

1. Watson et al. (2015): Recommended amount of sleep for a healthy adult (AASM and SRS consensus) — Adults should sleep 7 or more hours per night on a regular basis.
2. Hirshkowitz et al. (2015): National Sleep Foundation's sleep time duration recommendations — 7 to 9 hours recommended for adults 18 to 64, and 7 to 8 hours for adults 65 and older.
3. Blume, Garbazza and Spitschan (2019): Effects of light on human circadian rhythms, sleep and mood — Morning light helps shift the body clock earlier; evening light delays it.