Sleep length and wake-up times
What time to go to bed, how many hours you actually need, and why you can wake up tired after eight of them.
A tool for thisSleep Calculator
How Long Should You Snooze? 15 Minutes or 90 Minutes
Snoozing goes two ways: if time is short, cut it at about 15 minutes (total under 30); if you have time, sleep a full 90 to the cycle boundary. Why a 30-60 minute snooze feels groggiest.
How to Wake Up Refreshed: 5 Habits to Start Tonight
Wake up less groggy with five habits: a steady wake time, waking at the end of a sleep cycle, morning light, and the mistakes that prolong grogginess.
Minimum Sleep Required: 7+ Hours for Most Adults
Compare the US adult minimum of 7+ hours with the recommended 7–9 hours. See targets by age and a 2-week plan to estimate your own needs.
How Long Does It Take to Fall Asleep? The 10-20 Minute Range
Healthy adults usually fall asleep in 10–20 minutes. More than 30 minutes several nights a week is the sign to adjust — here is what to try tonight.
How Long Is a Sleep Cycle? 90 Minutes, 80–110 Range, Stages
A sleep cycle averages 90 minutes, but real cycles run 80–110. See NREM, REM, 4–6 cycles per night, and how to time wake-ups without over-tuning.
What Time Should I Go to Bed to Wake Up at 6 AM? Bedtime Chart
Wake at 6 AM? Aim for about 10:45 PM for 7 hours of sleep, with 15 minutes to fall asleep. Compare 6, 7, 7.5 and 8-hour bedtimes for every wake time from 5 to 9 AM.
Why Do You Wake Up Tired After 8 Hours of Sleep? 7 Reasons
Still tired after 8 hours of sleep? 7 common reasons, from sleep inertia to late caffeine and possible sleep apnea, plus 4 changes to try tonight.
