Data
Surprising facts and rankings built from public datasets. Every number links to its primary source, with the sample size, the method and a confidence label. Download the data and check it yourself.
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- FactWild elephants sleep about 2 hours a dayTwo wild African elephant matriarchs tracked for about five weeks slept an average of 2.0 hours a day (2.3 h and 1.8 h), mostly between 02:00 and 06:00, and sometimes went about 46 hours without sleeping.Confidence: Single study
- FactThere's no clear evidence that adults sleep less than 50 years agoA meta-analysis of 168 studies (257 data points, 6,052 healthy adults aged 18–88) that measured sleep objectively between 1960 and 2013 found no significant link between the year of a study and how long people slept. Reviews of self-reported sleep are mixed, though, and some large surveys do show a decline.Confidence: Debated
- FactUS melatonin use rose about fivefold in two decadesThe share of US adults who reported taking melatonin in the past 30 days rose from 0.4% in 1999–2000 to 2.1% in 2017–2018, with almost all of the rise after 2009–2010.Confidence: Solid
- FactYour body clock runs latest at about 20In ~25,000 people, the midpoint of sleep on free days drifted later through adolescence and peaked at about age 20 (19.5 for women, 20.9 for men) before moving steadily earlier for the rest of life.Confidence: Solid
- FactStarting school 55 minutes later gave Seattle teens 34 more minutes of sleepAfter Seattle moved high-school start time from 07:50 to 08:45, students' median wake-up on school days moved 44 minutes later and their median school-night sleep grew by 34 minutes, measured with wrist actigraphy.Confidence: Single study
- FactFor over a century, experts have told kids to sleep about 37 minutes more than they doAcross 32 sets of children's sleep recommendations published from 1897 to 2009, recommended sleep exceeded children's actual sleep in 144 of 173 matched comparisons (83%), by 37 minutes on average. Recommendations fell by 0.71 min a year, almost exactly as fast as actual sleep (0.73 min a year).Confidence: Single study
Rankings
- RankingWhich animals sleep the least?Giraffes sleep 1.9 hours a day, the least of any mammal in the dataset.
- RankingWhich animals sleep the most?The little brown bat sleeps 19.9 hours a day, more than any other mammal on record.
- RankingWhich countries go to bed the latest?Oura Ring users in Russia fall asleep at 00:33 on weekdays, nearly two hours after South Africans (22:38).
- RankingWhich countries sleep the least?Oura Ring users in Japan sleep 6 h 6 min on weekday nights, almost an hour less than in New Zealand.
- RankingHow much do Americans sleep at each age?Americans sleep least in their early 40s (8.65 h a day) and most as teenagers (9.89 h).
- RankingWhich US states sleep the worst?In Hawaii 45.9% of adults sleep less than 7 hours a night, the highest share of any state.
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