Sleep Calculator
Calculate the best time to go to bed or wake up based on sleep cycles. Each cycle lasts about 90 minutes, and waking up at the end of a cycle helps you feel refreshed.
Use this calculator to compute what time to go to bed or get up to wake up refreshed between sleep cycles. Click the settings to change sleep cycle length or the time you take to fall asleep.
⚙️ Calculator Settings
Use this calculator to compute what time to wake up or go to bed to get a given number of hours of sleep. When counting, please deduct the time taken to fall asleep, which can be very different for different people.
⚙️ Calculator Settings
Understanding Sleep Cycles
Sleep describes a recurring state in which the body and mind are at rest, reducing muscle activity, interaction with surroundings, and the ability to react to stimuli. The ability to react to stimuli is one of the distinguishing factors between the states of sleep and wakefulness.
What Are Sleep Cycles?
The sleep cycle can be defined as the oscillation between non-REM (rapid eye movement) and REM sleep. Sleep timing is largely based on hormonal signals from the circadian clock. The circadian clock exhibits a regular rhythm that corresponds to outside signals (such as night/day) that can persist even if the outside signals suddenly disappear.
Typically, a person's body cycles between non-REM and REM sleep over a period of 90 minutes on average, and should occur 4–6 times in a good night's sleep. Non-REM sleep begins, eventually moving into slow-wave sleep, or deep sleep. During this period, body temperature and heart rate fall, and the brain uses less energy.
REM and Non-REM Sleep
During sleep, the brain expends significantly less energy than it does when a person is awake, particularly during non-REM sleep. REM sleep is a type of sleep characterized by rapid eye movements, muscle paralysis, and vivid dreams.
REM sleep typically comprises a smaller proportion of sleep time, and is most known for when dreams or nightmares most frequently occur. Deprivation of REM sleep can result in anxiety, irritability, and difficulty concentrating.
How Much Sleep Do I Need?
Sleep is far from perfectly understood, and the amount of sleep a person needs can vary largely based on certain metrics, such as age. Very generally, researchers have found that achieving 6–7 hours of sleep per night correlates with a number of positive health outcomes.
Below are the CDC's recommendations for the number of hours a person should sleep based on age:
| Age Group | Recommended Hours of Sleep Per Day |
|---|---|
| 0–3 months | 14–17 hours |
| 4–12 months | 12–16 hours per 24 hours (including naps) |
| 1–2 years | 11–14 hours per 24 hours (including naps) |
| 3–5 years | 10–13 hours per 24 hours (including naps) |
| 6–12 years | 9–12 hours per 24 hours |
| 13–18 years | 8–10 hours per 24 hours |
| 18–60 years | 7 or more hours per night |
| 61–64 years | 7–9 hours |
| 65 years and older | 7–8 hours |
Sleep Quality Tips
- Avoid screens at least 30 minutes before bed — blue light suppresses melatonin production.
- Keep your room cool — the ideal sleeping temperature is between 60–67°F (15–19°C).
- Limit caffeine after 2 PM — it can stay in your system for 6–8 hours.
- Create a bedtime routine — consistent pre-sleep habits signal your body it's time to rest.
- Exercise regularly — but avoid vigorous activity within 2 hours of bedtime.
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People Also Ask
Q: How does the sleep calculator work?
It uses 90-minute sleep cycles. Most people take about 14 minutes to fall asleep. The calculator adds this to complete sleep cycles for optimal wake-up or bedtime.
Q: How much sleep do adults need?
Adults need 7-9 hours of sleep per night. The National Sleep Foundation recommends 8 hours for most adults.
Q: Why do I feel tired even after 8 hours of sleep?
You may be waking up mid-sleep cycle. Our calculator helps you time your sleep to wake up at the end of a cycle, when you feel most refreshed.
