{
  "type": "fact",
  "url": "https://karelbusta.dev/data/sleep/sleep-duration-has-not-declined",
  "title": "There's no clear evidence that adults sleep less than 50 years ago",
  "claim": "A 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.",
  "description": "Lab and actigraphy studies from 1960–2013 show no trend in adult sleep time. Surveys are mixed, so the \"sleep-loss epidemic\" is unproven, not disproven.",
  "confidence": "debated",
  "published": "2026-10-14",
  "context": "Objective data show no secular decline, but they come with a big caveat. The studies were mostly small lab samples of screened \"normal sleepers,\" often on fixed 8-hour schedules. Few separated women from men (17 data points), so they say little about how the general population sleeps at home. The survey evidence points in different directions. Bin et al.'s 2013 analysis of 328,018 adults found that short sleep (6 h or less) became more common only in Italy, and less common in Sweden, the UK and the US. But the CDC's National Health Interview Survey shows US age-adjusted sleep falling from 7.40 h in 1985 to 7.18 h in 2012, with the share of adults sleeping 6 hours or less rising from 22.3% to 29.2% (Ford et al. 2015). Weekday sleep in the Munich ChronoType survey also fell over 2002–2010, by about 30 minutes as cited by Youngstedt et al. Survey wording differs from study to study, so the fairest reading is that a large, broad decline in adult sleep has not been shown, while smaller shifts in particular countries and groups remain possible.",
  "sources": [
    {
      "authors": "Youngstedt SD, Goff EE, Reynolds AM, Kripke DF, Irwin MR, Bootzin RR, Khan N, Jean-Louis G",
      "journal": "Sleep Medicine Reviews",
      "sampleSize": "168 studies, 257 data points, 6,052 adults",
      "title": "Has adult sleep duration declined over the last 50+ years?",
      "url": "https://doi.org/10.1016/j.smrv.2015.08.004",
      "year": 2016
    },
    {
      "authors": "Bin YS, Marshall NS, Glozier N",
      "journal": "Sleep Medicine Reviews",
      "sampleSize": "12 studies, 15 countries, 1960s–2000s",
      "title": "Secular trends in adult sleep duration: a systematic review",
      "url": "https://doi.org/10.1016/j.smrv.2011.07.003",
      "year": 2012
    },
    {
      "authors": "Bin YS, Marshall NS, Glozier N",
      "journal": "American Journal of Epidemiology",
      "sampleSize": "38 time-use surveys, 328,018 adults, 10 countries",
      "title": "Sleeping at the limits: the changing prevalence of short and long sleep durations in 10 countries",
      "url": "https://doi.org/10.1093/aje/kws308",
      "year": 2013
    },
    {
      "authors": "Ford ES, Cunningham TJ, Croft JB",
      "journal": "Sleep",
      "sampleSize": "324,242 US adults (National Health Interview Survey)",
      "title": "Trends in self-reported sleep duration among US adults from 1985 to 2012",
      "url": "https://doi.org/10.5665/sleep.4684",
      "year": 2015
    }
  ],
  "method": "Youngstedt et al. searched for studies published from 1960 to 2013 that measured total sleep time objectively, by polysomnography (PSG) or actigraphy, in presumably healthy adults under minimally disturbed conditions such as baseline or placebo nights. Of more than 3,500 studies screened, 168 qualified. They gave 257 data points: 225 from PSG and 32 from actigraphy. Sleep time was regressed on study year with age adjustment, weighted for sample size. It was also analysed by 10-year age band, by PSG versus actigraphy, and by fixed versus habitual sleep schedules. None of these analyses found a significant association. Examples: all data b = 0.03, p = 0.56; actigraphy b = −0.17, p = 0.38; habitual schedules b = 0.13, p = 0.10. The chart instead shows Bin et al.'s 2012 systematic review of repeated national surveys of self-reported sleep.",
  "chart": {
    "data": [
      {
        "label": "Increased",
        "value": 7
      },
      {
        "label": "Decreased",
        "value": 6
      },
      {
        "label": "Inconsistent",
        "value": 2
      }
    ],
    "note": "Bin, Marshall & Glozier 2012, abstract (Results): increased in Bulgaria, Poland, Canada, France, Britain, Korea and the Netherlands (0.1–1.7 min per night per year); decreased in Japan, Russia, Finland, Germany, Belgium and Austria (0.1–0.6 min per night per year); inconsistent results for the United States and Sweden. Only the abstract of this review was checked.",
    "title": "Self-reported adult sleep, 1960s–2000s: did it rise or fall?",
    "type": "column",
    "unit": "countries",
    "x": "label",
    "y": "value",
    "yLabel": "Number of countries"
  },
  "dataset": null,
  "ranking": null,
  "related": [
    "https://karelbusta.dev/data/sleep/hunter-gatherers-sleep-less",
    "https://karelbusta.dev/data/sleep/kids-told-to-sleep-more-for-100-years",
    "https://karelbusta.dev/data/sleep/melatonin-use-rose-fivefold",
    "https://karelbusta.dev/data/sleep/latest-bedtime-at-20"
  ]
}