Best time to wake up
Going to bed now, or at a set time? The wake-up time calculator adds full 90-minute cycles to your bedtime so the alarm goes off at the end of a cycle.
Wake-up time calculator
Wake-up times if you go to bed at 11:00 PM
- 3 cycles · 4 h 30 min of sleep · the next dayShort night
- 4 cycles · 6 h of sleep · the next dayShort night: below the 7+ hours most adults need (CDC)
- 5 cycles · 7 h 30 min of sleep · the next dayRecommended for most adults
- 6 cycles · 9 h of sleep · the next dayRecommended for most adults
Includes 15 minutes to fall asleep and 90-minute cycles. 5–6 cycles give most adults the 7+ hours they need.
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 the wake-up calculator works
It does the bedtime sum in reverse: your bedtime, plus the minutes you need to fall asleep, plus 90 minutes for each cycle. Cycles average about 90 minutes [2], so with a 15-minute fall-asleep time and an 11:00 PM bedtime the options are:
| Cycles | Wake-up time | Sleep |
|---|---|---|
| 3 | 4.5 hours | |
| 4 | 6 hours | |
| 5 | 7.5 hours | |
| 6 | 9 hours |
The 5- and 6-cycle times (6:45 AM and 8:15 AM) give 7.5 and 9 hours, in line with the 7+ hours recommended for adults [3].
Why wake at the end of a cycle?
Each cycle moves from light sleep into deep sleep and then REM sleep. NINDS describes stage 3 as the deep sleep you need to feel refreshed, which occurs in longer periods during the first half of the night, and notes that it may be difficult to awaken you during it [4]. Being woken from deep sleep can cause grogginess [5].
That grogginess has a name: sleep inertia. Researchers describe it as a period of impaired performance after waking that fades as you stay awake, and it is worse after sleep loss [6]. Timing your alarm to the end of a cycle is a simple way to try to avoid the worst of it, though no calculator can know exactly which stage you are in.
Going to bed now
Press “Sleep now” and the calculator uses the current time on your device. If you plan to read for a while first, enter the time you expect to turn the light off instead. The results update instantly.
If it’s already late and the 5-cycle time is after your alarm has to go off, the honest answer is that you won’t get the recommended amount tonight. Choosing a 4-cycle wake-up may feel easier than waking mid-cycle, but try to make it up with a regular earlier bedtime rather than relying on it.
Tips for waking up more easily
- Keep a consistent schedule. CDC lists going to bed and getting up at the same time every day among habits that can improve sleep [7].
- Avoid caffeine late in the day. It can still disrupt sleep when taken 6 hours before bed [8]; try the caffeine cutoff calculator.
- Get up when the alarm goes off. Snoozing can mean dozing back into deeper sleep [5].
- Look at the total, not just the timing. Waking at the end of a cycle after 4.5 hours is still a short night.
Need a bedtime for a fixed alarm instead? Use the bedtime calculator, or go straight to a popular time such as 6 AM or 7 AM.
If you wake up tired every day
Regularly waking up unrefreshed after enough time in bed can have many causes. NHS guidance suggests seeing a GP if changing your sleeping habits hasn’t helped, if you’ve had trouble sleeping for months, or if it is affecting your daily life [9]. CDC also advises talking to a healthcare provider if you regularly have problems sleeping [7].
Related guides
Find out what happens in each stage of sleep and how much sleep you need.
- Sleep cycles explained: the stages, REM, and why cycles vary.
- How much sleep do you need by age?: the recommended hours for every age group.
- Sleep FAQ: 26 common questions, answered with sources.
Frequently asked questions
What time should I wake up if I go to bed now?
Press “Sleep now”. The calculator adds your fall-asleep time and then 3 to 6 cycles of 90 minutes, and lists the wake-up times with the hours of sleep for each.
What is the best time to wake up?
There isn’t one best clock time. The best alarm time is one that comes after enough sleep (7+ hours for adults [3]) and at the end of a cycle rather than in the middle of deep sleep.
Is it bad to wake up during deep sleep?
It isn’t harmful, but it can feel bad. Deep sleep is the stage in which it may be difficult to awaken you [4], and waking from it can cause grogginess [5], known as sleep inertia [6].
What is sleep inertia?
The grogginess you feel right after waking. A 2019 review describes it as cognitive performance decrements that dissipate as time awake increases, made worse by prior sleep loss and by the time of day you wake [6].
Should I hit snooze?
The Sleep Foundation advises against hitting snooze after a nap because it risks entering deeper sleep [5]. Setting the alarm for the time you actually need to get up avoids the problem.
Why does the list start at 3 cycles?
Three cycles (4.5 hours) is the shortest option that is still a whole number of cycles. It is marked as a short night: useful to know, but not enough sleep for an adult.
Can I use the 24-hour clock?
Yes. Choose “24-hour” under Clock; the choice is remembered on this device.
Why is my result different from another calculator?
Calculators differ in the fall-asleep time they assume (often 14 or 15 minutes) and some ignore it. Check that the same fall-asleep time and cycle length are used.
Sources
- Sleep Foundation: How Long Should It Take to Fall Asleep?. August 21, 2025. Accessed October 21, 2026.
- Sleep Foundation: Stages of Sleep: What Happens in a Normal Sleep Cycle?. July 25, 2025. Accessed October 21, 2026.
- 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.
- NINDS (NIH): Brain Basics: Understanding Sleep. February 25, 2025. Accessed October 21, 2026.
- Sleep Foundation: Napping: Benefits and Tips. May 27, 2026. Accessed October 21, 2026.
- Peer-reviewed review (open access): Sleep inertia: current insights (Hilditch & McHill, Nat Sci Sleep 2019;11:155–165). 2019. Accessed October 21, 2026.
- CDC: About Sleep. May 15, 2024. Accessed October 21, 2026.
- PubMed: Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed (Drake et al., J Clin Sleep Med 2013;9(11):1195–1200). 2013. Accessed October 21, 2026.
- NHS: Insomnia. Page last reviewed 19 March 2024. Accessed October 21, 2026.
Last reviewed by the CycleRest team (sources re-checked; no medical reviewer). Editorial policy