Sleep Statistics: Performance, Recovery, and Health Data

33.2% of US adults reported short sleep, under 7 hours in a 24-hour period, in 2020

Behavioral Risk Factor Surveillance System data. County rates ranged from 23.8% in Boulder County, Colorado, to 48.4% in Greene County, Alabama; about a third of adults also reported short sleep in 2014.

The National Sleep Foundation recommends 7-9 hours of sleep for adults, 7-8 hours for adults over 65 and 8-10 hours for teenagers

An 18-member expert panel from 12 organizations. Durations outside the range may be appropriate for some people, but far outside it is rare.

A week of 5-hour nights lowered daytime testosterone by 10-15% in young healthy men

Ten men, eight nights of 5-hour bedtimes in the laboratory. For comparison, normal ageing lowers testosterone by 1-2% a year.

One night without sleep cut muscle protein synthesis by 18%, raised cortisol by 21% and lowered testosterone by 24%

Randomized crossover in 13 healthy young adults (7 men, 6 women). Markers of muscle protein breakdown did not change.

A week of 5-hour nights reduced insulin sensitivity by 20% on an intravenous glucose test and by 11% on the clamp

20 healthy men aged 20-35 in a 12-day inpatient study with diet and activity controlled; salivary cortisol rose 51%.

Partial sleep deprivation increased energy intake by 385 kcal a day without changing energy expenditure

Meta-analysis of 11 studies with 172 participants; the extra intake was higher in fat and lower in protein.

Short sleepers had higher odds of obesity: odds ratio 1.55 in adults and 1.89 in children

Meta-analysis of 634,511 people in cross-sectional studies. Each hour less sleep went with 0.35 more BMI units in adults; cause and effect could not be established.

Short sleep was associated with a 12% higher risk of death (relative risk 1.12), and long sleep with a 30% higher risk (1.30)

Meta-analysis of 16 prospective studies with 1,382,999 people and 112,566 deaths; sleep was self-reported, and definitions of short and long varied.

Short sleep was associated with a 48% higher risk of developing or dying of coronary heart disease (RR 1.48) and 15% for stroke, but not with total cardiovascular disease

15 prospective studies with 474,684 people. Long sleep was linked to higher risk of all three (coronary heart disease 1.38, stroke 1.65, total CVD 1.41).

Extending sleep by an average of 111 minutes a night cut a timed sprint from 16.2 to 15.5 seconds and raised free-throw and 3-point accuracy by about 9% in college basketball players

11 Stanford varsity players aimed for at least 10 hours in bed for 5-7 weeks. Reaction time, daytime sleepiness and mood also improved; there was no control group.

Elite athletes spent 8 h 18 min in bed but slept 6 h 30 min a night on average, and slept less before training days than before rest days

Activity monitors on 70 nationally ranked athletes from seven sports for two weeks. Early-morning sessions cut sleep and raised pre-training fatigue.

Adolescent athletes who slept under 8 hours a night were 1.7 times more likely to have had an injury

112 athletes aged 12-18 at one school, with injuries from athletic-department records. Each additional school grade raised the odds 1.4-fold.

Adolescents who chronically slept poorly had 1.58 times the odds of sports or musculoskeletal injury

Meta-analysis of seven studies. The effect of a single poor night on injury could not yet be determined.

Deep slow-wave sleep fell from 18.9% of sleep at ages 16-25 to 3.4% at ages 36-50, alongside a major drop in growth-hormone secretion

149 healthy men aged 16-83. Independent of age, the amount of growth hormone secreted was tied to the amount of slow-wave sleep.

Brief naps of 5-15 minutes improve alertness almost immediately for 1-3 hours, while naps over 30 minutes can cause grogginess first

Review. Longer naps give benefits that last up to many hours once the sleep inertia passes; early afternoon is the most favourable time.

Some maximal physical efforts hold up after sleep loss, while the few studies in athletes report reduced sport-specific performance

Review of sleep restriction and deprivation; cognitive performance became slower and less accurate in numerous studies.