What happens if I sleep less than recommended?

Chronic sleep deprivation raises the risk of obesity, heart disease, type 2 diabetes, weakened immunity, and impaired cognitive function.

Is it bad to sleep too much?

Consistently sleeping over 9–10 hours as an adult may be a sign of an underlying health condition. Occasional longer sleep during recovery is normal.

What are sleep cycles?

Sleep cycles last approximately 90 minutes. A full night of 7.5–9 hours covers 5–6 complete cycles. Waking mid-cycle often causes grogginess.

Sleep Calculator — How Much Sleep Do You Need?

The Sleep Calculator tells you how many hours of sleep you need per night based on your age, following guidelines from the National Sleep Foundation. Sleep is essential for memory consolidation, immune function, metabolism, and mental health. Most adults need 7–9 hours, but the optimal amount varies by age group.

Age(years)

Wake-up Time (hour, 0–23)(hour)

How to Use This Calculator

1
Enter your age in years.
2
Enter what time you need to wake up.
3
Click Calculate to see your recommended sleep duration.
4
Count back from your wake time to find your ideal bedtime.

Frequently Asked Questions

Most adults (18–64) need 7–9 hours per night. Older adults (65+) typically need 7–8 hours. Regularly getting fewer than 7 hours is linked to health risks.

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