How much sleep do adults need across the lifespan

When examining how much sleep do adults need, published guidance points to two primary consensus statements issued in 2015. One panel established an appropriate range of 7 to 9 hours for younger adults and adults, and 7 to 8 hours for older adults, while a second panel concluded that adults aged 18 to 60 should obtain 7 or more hours per night on a regular basis. Both groups noted that natural requirements vary considerably across individuals.

Consensus panels and their recommendations

In 2015 the National Sleep Foundation published an update of its sleep duration recommendations. The foundation convened an 18-member multidisciplinary expert panel representing 12 stakeholder organisations, which evaluated the scientific literature and reached its ranges through a formal consensus and voting process using the RAND/UCLA Appropriateness Method. Each range was designated as recommended, may be appropriate, or not recommended.^[1][2]

For healthy individuals with normal sleep, the panel considered 7 to 9 hours appropriate for young adults and adults, and 7 to 8 hours for older adults. The ranges were stated as guidelines for healthy individuals.^[1]

A separate 2015 consensus statement from two professional sleep organisations, produced by a panel of 15 experts in sleep medicine and research with a modified RAND Appropriateness Method, set out to define the sleep duration for adults aged 18 to 60 and concluded that adults should sleep 7 or more hours per night on a regular basis. It added that more than 9 hours a night on a regular basis may be appropriate for young adults, for people recovering from sleep debt and for people who are ill, and that for others it is uncertain whether sleeping more than 9 hours is associated with health risk. The statement also says that individual variability in sleep need is influenced by genetic, behavioural, medical and environmental factors.^[3]

Individual variation and age differences

The same summary states that sufficient sleep duration varies across the lifespan and from person to person, that durations outside the recommended range may be appropriate, and that deviating far from the normal range is rare.^[1]

CIBDOL · Individual variation and age differences

Changes in duration also occur across adulthood. In a meta-analysis of 65 studies with 3577 participants aged 5 to 102, using all-night polysomnography or actigraphy, total sleep time in adults decreased significantly with age. After age 60 only sleep efficiency continued to decrease significantly, and the size of the age effects depended on how carefully the studies had screened their participants.^[7]

What adults report in large population studies

What people actually report was charted in a 2021 meta-analysis of questionnaire data from about 1.1 million people: 200,358 people aged 1 to 100 from 36 studies in the Netherlands, 471,759 people aged 40 to 69 in the United Kingdom and 409,617 adults in the United States. Across the pooled data one in four people slept less than the age-specific recommendation, but only 5.8 percent slept outside the range classed as acceptable. Among adults, 6.5 percent reported a total sleep time under 6 hours, and total sleep time was similar across the three countries.^[4]

National sampling shows comparable patterns. In a 2014 United States survey of 444,306 adult respondents, 65.2 percent reported sleeping 7 hours or more, and more than one third reported typically sleeping less than 7 hours in a 24-hour period.^[5]

Reported hours compared with objective measures

In one population-based sample, reported hours ran higher than measured hours. In 669 middle-aged adults in Chicago who wore a wrist actigraph for two waves of three days each, average measured sleep was 6 hours while the average reported figure was 6.8 hours, and the correlation between the two was 0.47. The authors' model estimated that people sleeping 5 hours over-reported by 1.2 hours and people sleeping 7 hours by 0.4 hours.^[6]

In the same 1.1-million-person analysis, the measuring method changed the direction of one comparison: women aged 41 and over reported sleeping shorter times or slightly less efficiently than men, whereas actigraphy estimated that they slept longer and more efficiently than men.^[4]

Duration under extended bed rest

Laboratory protocols evaluate what happens when time in bed is substantially increased. In an inpatient study, 18 older and 35 younger healthy men and women were given 12 hours of sleep opportunity at night plus 4 hours in the afternoon for 3 to 7 days. Total daily sleep, initially longer than their habitual sleep at home, declined to stable values of 7.4 hours in the older group and 8.9 hours in the younger group, a difference of 1.5 hours.^[8]

In 17 healthy volunteers aged 18 to 32 whose habitual time in bed ranged from 6.1 to 10.3 hours, total sleep time on the first day of a 16-hour sleep opportunity rose by an average of 4.9 hours over their habitual time in bed. By the third day, those with shorter habitual time in bed were still sleeping more than those with longer habitual time in bed, and the authors concluded that people with shorter habitual sleep carry a higher sleep debt and that variation in habitual sleep duration may primarily reflect self-selected sleep restriction or wake extension.^[9]

This article quotes published consensus ranges as the statements of the panels that issued them and reports sleep durations as what each study measured or recorded in its sample. It sets no target for the reader and gives no medical advice.