CycleRest

What time should I go to bed?

Enter the time you need to wake up. The bedtime calculator counts back in 90-minute sleep cycles, allowing for the time you take to fall asleep.

Bedtime calculator

Time to fall asleep

Most healthy people fall asleep within 15–20 minutes of lying down [1].

Advanced: cycle length

Cycles average about 90 minutes but vary [2]. If you know your usual cycle from experience, you can change it here.

Clock

Bedtimes for a 7:00 AM wake-up

  1. 6 cycles · 9 h of sleep · the night beforeRecommended for most adults
  2. 5 cycles · 7 h 30 min of sleep · the night beforeRecommended for most adults
  3. 4 cycles · 6 h of sleep · same dayShort night: below the 7+ hours most adults need (CDC)
  4. 3 cycles · 4 h 30 min of sleep · same dayShort night

Includes 15 minutes to fall asleep and 90-minute cycles. Aim for the options marked “recommended” (5–6 cycles, 7+ hours).

This calculator gives general estimates based on average 90-minute sleep cycles. It isn’t medical advice. If you have ongoing trouble sleeping, loud snoring, or daytime sleepiness, talk to a doctor.

How accurate is this? It’s an estimate. Sleep cycles average about 90 minutes, but they vary: the first cycle of the night is often 70–100 minutes and later ones 90–120 minutes [2]. That’s why you can change the cycle length and the time you take to fall asleep. Nobody can predict the exact stage you’ll be in at a given minute.

How to choose your bedtime

  1. Enter the time your alarm has to go off.
  2. Pick how long you usually take to fall asleep: 5, 15 or 30 minutes, or type the exact number.
  3. Read the four bedtimes. The top two (6 and 5 cycles) are marked “recommended for most adults”.
  4. Be in bed with the lights off at that time. Start winding down earlier.

The bedtime calculator only works with whole cycles. Cycles average about 90 minutes [2], and REM sleep first occurs about 90 minutes after you fall asleep [3]. Timing the alarm to the end of a cycle aims to avoid waking you from deep sleep, which can leave you groggy [4].

Bedtimes for common wake-up times

These bedtimes allow 15 minutes to fall asleep. Each time has its own page with a full table, tips and answers.

Bedtimes by wake-up time (15 minutes to fall asleep)
Wake-up time6 cycles (9 h)5 cycles (7.5 h)4 cycles (6 h)
4:00 AM
4:30 AM
5:00 AM
5:30 AM
6:00 AM
6:30 AM
7:00 AM
7:30 AM
8:00 AM
9:00 AM

Pick the right number of cycles

For adults, the American Academy of Sleep Medicine and Sleep Research Society recommend 7 or more hours a night on a regular basis, and say regularly sleeping less than 7 hours is associated with adverse health outcomes [5]. Five cycles (7.5 hours) is the shortest option that meets that guidance with the default settings, so it is usually the one to aim for. Six cycles (9 hours) suits people who need more, and it is closer to what teenagers need: 8–10 hours for ages 13–18 [6].

The 4-cycle and 3-cycle bedtimes are there for nights when you genuinely can’t get more, for example before an early flight. They may help you avoid waking in the middle of a cycle, but they don’t give you enough sleep.

What if the times don’t work for you?

Everyone is different. If you keep waking a little before the alarm, your cycles may be shorter than 90 minutes; if you wake up groggy, they may be longer. Open “Advanced: cycle length” and try 80 or 100 minutes. You can also change the fall-asleep time if you know you take longer on some nights. The calculator remembers these settings on this device.

A regular routine helps too. CDC lists going to bed and getting up at the same time every day, keeping the bedroom quiet and cool, turning off devices at least 30 minutes before bedtime, and avoiding caffeine in the afternoon or evening among habits that can improve sleep [7].

When a later wake-up time isn’t possible

If your mornings are fixed, the bedtime is the only part you can move. Working back from the alarm makes the trade-off visible: each cycle you add means going to bed 90 minutes earlier. If even the 5-cycle bedtime feels unrealistically early on most nights, it’s worth looking at what happens in the evening (late caffeine, screens, work), rather than accepting a short night as normal. If you regularly can’t sleep even when you go to bed on time, talk to a healthcare provider [7].

Related guides

Learn what happens during each cycle, or check how much sleep you need for your age.

Frequently asked questions

What time should I go to bed?

Count back from your wake-up time: subtract the minutes you need to fall asleep, then 90 minutes for each cycle. For most adults, 5 or 6 cycles (7.5 or 9 hours) meets the 7+ hours recommended [5].

Why does the calculator give four bedtimes?

They are for 6, 5, 4 and 3 full cycles. The first two are the recommended options; the last two are short nights for when you can’t get more sleep.

Should I include the time it takes to fall asleep?

Yes. If you take 15 minutes to fall asleep and don’t allow for it, every cycle shifts by 15 minutes. Most healthy people fall asleep within 15 to 20 minutes [1].

What if I fall asleep very quickly?

Set the fall-asleep time to 5 minutes or less. Note that the Sleep Foundation says falling asleep within minutes of lying down could be a sign of insufficient sleep or a medical condition [1].

Is 6 hours of sleep enough if it’s 4 full cycles?

Not for most adults. Waking at the end of a cycle may feel easier, but adults are advised to get 7 or more hours on a regular basis [5].

Is it better to sleep 6 or 7.5 hours?

7.5 hours. It is both a whole number of 90-minute cycles and above the 7-hour minimum recommended for adults [5].

What time should a teenager go to bed?

Teens 13–18 need 8–10 hours [6], so the 6-cycle (9-hour) bedtime is usually the better fit. See sleep by age.

Does the bedtime change on the night the clocks change?

The calculator shows ordinary clock times. On a daylight-saving night it adds a note: when clocks go back you get about an hour more sleep than shown, and when they go forward about an hour less.

Can I use this for a night shift?

Yes: enter the time you need to get up, even if it’s in the afternoon. The cycle maths works at any time of day, although daytime sleep is often harder.

Sources

  1. Sleep Foundation: How Long Should It Take to Fall Asleep?. August 21, 2025. Accessed October 21, 2026.
  2. Sleep Foundation: Stages of Sleep: What Happens in a Normal Sleep Cycle?. July 25, 2025. Accessed October 21, 2026.
  3. NINDS (NIH): Brain Basics: Understanding Sleep. February 25, 2025. Accessed October 21, 2026.
  4. Sleep Foundation: Napping: Benefits and Tips. May 27, 2026. Accessed October 21, 2026.
  5. AASM / SRS: Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the AASM and Sleep Research Society (Watson et al., J Clin Sleep Med 2015;11(6):591–592). 2015. Accessed October 21, 2026.
  6. AASM: Recommended Amount of Sleep for Pediatric Populations: A Consensus Statement of the American Academy of Sleep Medicine (Paruthi et al., J Clin Sleep Med 2016;12(6):785–786). 2016. Accessed October 21, 2026.
  7. CDC: About Sleep. May 15, 2024. Accessed October 21, 2026.

Last reviewed by the CycleRest team (sources re-checked; no medical reviewer). Editorial policy