{
  "type": "fact",
  "url": "https://karelbusta.dev/data/sleep/wild-elephants-sleep-2-hours",
  "title": "Wild elephants sleep about 2 hours a day",
  "claim": "Two 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.",
  "description": "Trunk-implanted activity monitors on two wild African elephant matriarchs recorded about 2 h of sleep a day, the lowest reported for any mammal.",
  "confidence": "single study",
  "published": "2026-10-14",
  "context": "The authors say 2 hours is the shortest daily sleep recorded for any mammal. It is well below the 3.1–6.9 hours from earlier observational studies, most of them on captive elephants. That fits the broader pattern that bigger animals sleep less. The matriarchs slept in several short bouts, often standing. They lay down only every third or fourth night, which led the authors to suggest elephants may not get REM sleep every day. On five occasions an elephant went about 45–49 hours without sleeping and in all but one case showed no extra recovery sleep afterwards. Caveats: this is two animals, both matriarchs, followed for about five weeks in a single stretch of mild weather, and sleep was inferred from trunk stillness rather than measured from brain activity.",
  "sources": [
    {
      "authors": "Gravett N, Bhagwandin A, Sutcliffe R, Landen K, Chase MJ, Lyamin OI, Siegel JM, Manger PR",
      "journal": "PLOS ONE",
      "sampleSize": "2 wild African elephant matriarchs, 14 April–18 May (70 elephant-nights)",
      "title": "Inactivity/sleep in two wild free-roaming African elephant matriarchs – Does large body size make elephants the shortest mammalian sleepers?",
      "url": "https://doi.org/10.1371/journal.pone.0171903",
      "year": 2017
    }
  ],
  "method": "Researchers in Chobe National Park, Botswana, implanted an actiwatch under the skin of each matriarch's trunk and fitted a GPS collar with a gyroscope, plus a portable weather station. In captive studies a still trunk reliably marks behavioural sleep, so any period of trunk inactivity lasting 5 minutes or more was scored as sleep. The gyroscope showed whether the animal was standing or lying down. This is a proxy. No EEG was recorded, trunk actigraphy has never been validated against polysomnography, and the authors note it may overestimate sleep, which would make 2 hours an upper bound.",
  "chart": {
    "data": [
      {
        "label": "Wild matriarch 1 (2017)",
        "value": 2.3
      },
      {
        "label": "Wild matriarch 2 (2017)",
        "value": 1.8
      },
      {
        "label": "Zoo elephants (Kühme 1963)",
        "value": 4.17
      },
      {
        "label": "Circus elephants (Kurt 1960)",
        "value": 5.92
      }
    ],
    "highlight": [
      "Wild matriarch 1 (2017)",
      "Wild matriarch 2 (2017)"
    ],
    "note": "Wild values from Results (\"Total daily sleep times…\"); combined mean 2.0 h (s.d. 1.2). Captive values from the paper's Table 1 summary of earlier studies, which used behavioural observation rather than actigraphy, so the methods are not identical.",
    "title": "Daily sleep in elephants, wild vs captive",
    "type": "bar",
    "unit": "h",
    "x": "label",
    "y": "value",
    "yLabel": "Total sleep per day"
  },
  "dataset": null,
  "ranking": null,
  "related": [
    "https://karelbusta.dev/data/sleep/bigger-animals-sleep-less",
    "https://karelbusta.dev/data/sleep/frigatebirds-sleep-in-flight",
    "https://karelbusta.dev/data/sleep/hunter-gatherers-sleep-less"
  ]
}