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SleepUncovered

Research summaries

The studies behind the answers

Each summary is the same shape: what they did, what they found, what it means for you. Plus a link to the original paper. No press-release exaggeration.

  1. Strong evidenceSleep, 2003 · 2003

    Van Dongen et al — the cumulative cost of sleep restriction

    • Lab study, 48 adults across four sleep schedules over 14 days.
    • Six-hour nights for two weeks produced cognitive deficits matching 24-hour total deprivation.
    • Subjective sleepiness plateaued after a few days — participants felt 'fine'.
    • Performance kept degrading regardless. The dose was cumulative.

    What it means — You cannot trust your own assessment of whether you're sleep-deprived. Track the input, not the feeling.

  2. Strong evidenceWhy We Sleep / Nature Communications · 2017

    Walker — sleep deprivation and natural killer cell activity

    • Healthy adults restricted to 4 hours of sleep for one night.
    • Natural killer cell activity dropped by 70% the following day.
    • Effect was dose-responsive — less sleep, more suppression.
    • Recovery to baseline took multiple nights of full sleep.

    What it means — The immune cost of short sleep is real and measurable, not abstract. One night moves the dial.

  3. Strong evidenceJAMA, 2009 · 2009

    Morin et al — CBT-I vs medication for chronic insomnia

    • Randomised trial comparing CBT-I and zolpidem in adults with chronic insomnia.
    • Six weeks: both treatments roughly equivalent on sleep onset and total sleep time.
    • 12 months: CBT-I gains held; pharmacological gains largely did not.
    • Combined treatment outperformed either alone — but CBT-I alone outperformed medication alone long-term.

    What it means — If you have chronic insomnia, CBT-I is the first-line treatment by every major guideline. The evidence is stronger than for any sleep drug.