How many hours of sleep do adults need?

Most adults need 7–9 hours. Teenagers need 8–10 hours, school-age children need 9–11 hours. Genetics play a role — true 'short sleepers' who genuinely thrive on 6 hours are rare.

What is REM sleep and why does it matter?

REM (Rapid Eye Movement) sleep is when most vivid dreaming occurs. It's essential for memory consolidation, emotional processing, and learning. REM sleep increases in later cycles — so cutting sleep short disproportionately reduces REM.

Why do I feel groggy even after 8 hours?

You may have woken during deep sleep (sleep inertia) or have inconsistent sleep timing. Try keeping a fixed wake time every day, including weekends, to regulate your circadian rhythm.

Does napping affect nighttime sleep?

A 20–30 minute 'power nap' before 3 PM is generally safe and beneficial. Longer naps or naps taken later in the day can reduce sleep pressure and make it harder to fall asleep at night.

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