Sleep Calculator
Calculate optimal bedtimes or wake-up times based on 90-minute sleep cycles. Wake up refreshed every morning.
Recommended Bedtimes
Sleep Recommendations by Age
Newborn (0–3 months)14–17 hours
Infant (4–11 months)12–15 hours
Toddler (1–2 years)11–14 hours
Preschool (3–5 years)10–13 hours
School age (6–13 years)9–11 hours
Teen (14–17 years)8–10 hours
Young adult (18–25)7–9 hours
Adult (26–64)7–9 hours
Older adult (65+)7–8 hours
Frequently Asked Questions
What is a sleep cycle?
A sleep cycle lasts approximately 90 minutes and includes light sleep, deep sleep (slow-wave), and REM (rapid eye movement) sleep. Waking up at the end of a complete cycle rather than mid-cycle helps you feel more alert and refreshed.
How many sleep cycles do I need per night?
Most adults need 5–6 complete sleep cycles (7.5–9 hours) per night. Young adults and teenagers typically need 6 or more cycles. Consistently sleeping fewer than 4 cycles (6 hours) is associated with impaired cognitive function and increased health risks.
Why do Nigerians often sleep less than recommended?
Factors include late-night social activities, inconsistent power supply (NEPA), night business and hustle culture, noisy urban environments, and longer commutes. Shift workers in industries like healthcare, security, and manufacturing face additional challenges.
Does the time you fall asleep matter?
Yes. Sleep before midnight tends to include more deep (slow-wave) sleep, which is the most physically restorative phase. Sleeping after midnight shifts the balance towards more REM sleep, which is important for memory but less physically restorative.
How long does it typically take to fall asleep?
Most people take 10–20 minutes to fall asleep. This calculator adds a 15-minute sleep onset allowance by default. If you typically take longer, factor this into your chosen bedtime.