How Much Sleep Do I Need? (By Age + Calculator)

Most adults hear that they should sleep “8 hours”, but the truth is more flexible. In this guide, you’ll learn how much sleep you really need at different ages – and how to use sleep cycles to wake up feeling more refreshed.

Recommended Sleep by Age

Sleep experts generally recommend the following amounts of sleep per night:

• Teenagers (14–17 years): 8–10 hours
• Young adults and adults (18–64 years): 7–9 hours
• Older adults (65+ years): 7–8 hours

These are average ranges. Some people feel great at the lower end, while others need a bit more. The key is how you feel during the day: focused, stable in mood, and not constantly tired.

Sleep Cycles and Total Sleep Time

Your brain sleeps in cycles of about 90 minutes. Each cycle includes light sleep, deep sleep, and REM sleep. Waking up in the middle of a deep sleep phase often makes you feel groggy – even if you slept “long enough”.

That’s why many people feel better with 7.5 hours (5 cycles) or 9 hours (6 cycles) than with a random number like 8 hours. Aligning your bedtime with full cycles can make a big difference.

Use the Sleep Calculator to Find Your Ideal Bedtime

You don’t have to calculate cycles in your head. Use the free Sleep Calculator on BestBedtime.net to find your best time to sleep and wake up. Simply choose when you want to wake up, and the calculator suggests several bedtimes based on 90-minute sleep cycles – including extra time to fall asleep.

Signs You’re Not Getting Enough Sleep

Even if you hit a certain number of hours, your body will tell you if it’s not enough. Common signs include:

• Feeling very tired when you wake up most days
• Needing a lot of caffeine to get through the day
• Difficulty concentrating or remembering things
• Mood swings or increased irritability

If this sounds like you, try increasing your sleep in steps of 30 minutes and use the sleep calculator to align your bedtime with full sleep cycles.