Guide · Sleep

How many hours of sleep you need by age: the chart and what matters

From newborns to older adults, how much sleep each stage of life calls for, according to the consensus statements, and how to tell if yours is enough.

In this article

1. How many hours of sleep you need, by age
2. Adults: why 7 hours is the floor
3. Sleeping too little and too much: what long-term studies show
4. How sleep changes with age
5. How to tell if your sleep is enough
6. When to talk to a doctor
7. How to track your sleep hours
8. Frequently asked questions
9. Sources

How many hours of sleep you need, by age

The most widely used reference comes from a panel of 18 experts convened by the National Sleep Foundation, which reviewed the literature and voted on sleep ranges for each stage of life. The ranges below are those recommended for healthy people without a sleep disorder.

For children, the hours include naps. The American Academy of Sleep Medicine published its own paediatric recommendations in 2016, with very similar ranges.

The panel also made a point that often gets lost: sleep need varies from person to person. The ranges describe where most healthy people fall. Sleeping slightly outside them can be normal for someone; being far from them, habitually, is rare and deserves attention.

Adults: why 7 hours is the floor

In 2015, the American Academy of Sleep Medicine and the Sleep Research Society issued a consensus for adults only. The conclusion was direct: adults should sleep 7 hours or more per night, on a regular basis, to promote health.

Why the floor is 7 and not 6 shows up in lab experiments. In the classic study by Van Dongen and colleagues, 48 healthy adults were randomly assigned to sleep 4, 6 or 8 hours a night for 14 days in a row. Those on 6 hours built up losses in attention and working memory that, by the end of the two weeks, were equivalent to up to two full nights without sleep.

The most striking finding is another one: participants barely noticed the decline. The sleepiness they reported rose in the first days and then levelled off, while performance kept falling. In other words, feeling that you have got used to 6 hours is not a good measure of how much sleep you need.

A meta-analysis of 70 studies on short-term sleep deprivation confirmed that simple attention is the function most sensitive to lack of sleep. It is the lapse: the moment when the response simply does not come.

Sleeping too little and too much: what long-term studies show

A meta-analysis of 16 prospective studies, with more than 1.38 million people followed for 4 to 25 years, compared short sleepers, long sleepers and people in the middle range. Both extremes were associated with fewer years of life compared with the middle of the curve. People who sleep within the recommended range have the best longevity profile.

Two cautions when reading this finding:

• Sleeping a lot may be a sign, not a cause. Health conditions, depression and some medications increase time in bed. The authors themselves treat long sleep as a possible marker of other problems.
• Sleep was measured by questionnaire. People reported how much they slept. That carries error, because we tend to confuse time in bed with time asleep.

The practical message holds: 7 to 9 hours for adults is where health tends to be best. If you need much more than that to function, or sleep a lot and wake up tired, it is worth talking to a doctor.

How sleep changes with age

A meta-analysis of 65 studies, with 3,577 people aged 5 to 102, showed how sleep changes over a lifetime. In adults, total sleep time, sleep efficiency (the share of time in bed actually spent asleep), deep sleep and REM sleep decrease over the years. Lighter stages take up more room and awakenings in the middle of the night become more common.

This does not mean older people need less sleep. What changes is the ability to sustain it. The recommendation for people over 65 remains 7 to 8 hours.

The same study adds an observation that applies at every age: the changes were much smaller in studies that excluded people with sleep apnoea, depression, alcohol use or medications. Part of what looks like ageing of sleep is actually sleep affected by conditions that can be treated, such as sleep apnoea.

How to tell if your sleep is enough

Counting hours is a start, but the body gives other signs. Some indications that sleep is not enough:

• You need an alarm every day and, on days off, sleep much longer than on workdays.
• You fall asleep within minutes in any still situation, such as a meeting or the sofa after lunch.
• Your attention wavers in the afternoon, you lose the thread of conversations or reread the same sentence several times.
• You depend on coffee to get started and to get through the day.

A simple test is to observe your holidays. After a few days without an alarm, the body tends to settle near the amount it needs. If that number is much higher than what you sleep in your routine, there is a sleep debt.

Regularity also counts. Going to bed and waking up at similar times, including at weekends, helps the body clock prepare you to sleep at the right time.

A two-week test

• Choose a fixed wake-up time, including at weekends.
• Count back the range for your age and set your bedtime. Add the time you usually take to fall asleep.
• Note how you feel at 10 a.m. and 3 p.m., with a simple score.
• If you still wake up tired after the first week, move bedtime a little earlier and repeat for another week.

The goal is to find the point at which you wake up without effort and get through the afternoon without a sharp energy dip.

When to talk to a doctor

Sleeping little by choice is different from being unable to sleep. Seek an assessment if you:

• Have trouble falling or staying asleep on most nights, for weeks.
• Snore loudly, wake up choking, or someone has seen you stop breathing in your sleep.
• Feel very sleepy during the day even after sleeping 7 hours or more.
• Have started sleeping much more than before for no clear reason.

Insomnia, sleep apnoea and other sleep disorders can be treated, and the decision about treatment is made with your doctor. Habits such as a regular schedule, natural light in the morning and less caffeine in the afternoon help in any case.

How to track your sleep hours

The question "how many hours do I sleep" seems simple, but most people answer with their time in bed. The gap between lying down and sleeping can exceed an hour on bad nights. Measuring for a few weeks shows your real pattern: the average, the variation between weekdays and weekends, and how sleep responds to training, alcohol and stress.

Frequently asked questions

Sources

1. Hirshkowitz M et al. National Sleep Foundation's sleep time duration recommendations: methodology and results summary. Sleep Health, 2015. doi.org/10.1016/j.sleh.2014.12.010 · Evidence A
2. Watson NF et al. Recommended Amount of Sleep for a Healthy Adult: a joint consensus statement of the AASM and SRS. Sleep, 2015. doi.org/10.5665/sleep.4716 · Evidence A
3. Paruthi S et al. Recommended Amount of Sleep for Pediatric Populations: a consensus statement of the American Academy of Sleep Medicine. Journal of Clinical Sleep Medicine, 2016. doi.org/10.5664/jcsm.5866 · Evidence A
4. Van Dongen HP et al. The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. Sleep, 2003. doi.org/10.1093/sleep/26.2.117 · Evidence B
5. Lim J, Dinges DF. A meta-analysis of the impact of short-term sleep deprivation on cognitive variables. Psychological Bulletin, 2010. doi.org/10.1037/a0018883 · Evidence A
6. Cappuccio FP et al. Sleep duration and all-cause mortality: a systematic review and meta-analysis of prospective studies. Sleep, 2010. doi.org/10.1093/sleep/33.5.585 · Evidence A
7. Ohayon MM et al. Meta-analysis of quantitative sleep parameters from childhood to old age in healthy individuals. Sleep, 2004. doi.org/10.1093/sleep/27.7.1255 · Evidence A