8 year old child
- Input
- 8 anos | 8 years
- Expected output
- NSF 9-11 h | AASM 9-12 h
Both sources agree on a 9 hour floor; the AASM accepts up to 12.
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how many hours of sleep by age
Sleep need changes a lot over a lifetime: a newborn sleeps 14 to 17 hours a day and an adult 7 to 9. The numbers below come from two expert consensus statements, the National Sleep Foundation (NSF, 2015) and the American Academy of Sleep Medicine (AASM). The tool below opens on the By age tab.
Both sources agree on a 9 hour floor; the AASM accepts up to 12.
The same range in both sources. Sleeping 7 hours falls in the NSF "may be appropriate" band, and less than that is "not recommended".
Six hours sits in the NSF "may be appropriate" band, but below the AASM and SRS consensus.
Sleep need does not drop much with age, but sleep tends to become more fragmented.
It starts from the time you want to wake up (or lie down), adds or subtracts the time to fall asleep and multiples of the cycle length, 90 minutes by default. The results are times that land at the end of a cycle. Example: waking at 7 AM, 15 minutes to fall asleep and 5 cycles gives 11:15 PM.
The AASM and the Sleep Research Society recommend 7 or more hours a night. The National Sleep Foundation suggests 7 to 9 hours from 18 to 64 and 7 to 8 from 65. There is individual variation: some healthy people need a little more or less.
For babies and young children, yes: the ranges are per 24 hours and count daytime naps. For adults, the AASM and SRS consensus speaks of hours per night and the NSF of hours per day. The tool compares the hours of one night with those ranges.
For adults, the AASM consensus says more than 9 hours may be appropriate for young adults, people recovering from sleep debt and people who are ill, and that for others it is unclear whether there is a risk. If you need much more sleep than usual and still wake up tired, talk to a health professional.
The 90 minute cycle is an average: it varies from person to person and from night to night. This tool is educational, does not diagnose anything and cannot promise you will wake up refreshed.
To wake up at 7:00 AM, allowing 15 min to fall asleep and 90 min cycles, go to bed at one of these times:
End of cycle is an estimate: waking a few minutes earlier or later is normal, and real cycles change from night to night. Sleeping as long as your body needs matters more than hitting the exact minute.
A night is a sequence of cycles, each moving through light sleep (N1 and N2), deep sleep (N3) and REM sleep. Typical values in healthy young adults:
That is why cycles are not identical: the first is usually shorter (about 70 to 100 minutes) and the last ones longer (about 90 to 120). The 90 minute average is only a reference.
The 90 minute default is the population average. If you have measured your own cycle (for example with a sleep tracker) or feel you wake better with another value, adjust it between 70 and 120 minutes.
Frequent insomnia, loud snoring with breathing pauses or strong daytime sleepiness deserve a health professional's evaluation. No schedule calculation fixes a sleep disorder.