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Sleep CyclesEvidence & Dosage

90-minute cycles — deep sleep early, REM later in the night.

Studies last updated

Evidence at a glance

Total studies
367
With abstract
50
Meta / Systematic / RCT
134
Highly cited
50
Publication years
1991–2026

Sleep Cycles in the context of Sleep

This topic is part of our "Sleep" world. There you'll find methodology, evidence and the highest-impact levers — plus the order in which they sensibly build on each other.

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Top studies on Sleep Cycles

Ranked by influential-citation count and publication year.

  1. Epworth sleepiness scale: A meta-analytic study on the internal consistency.

    Sleep Med2023n=92,503Meta-Analysis167 influential citations

    <h4>Objective/background</h4>The Epworth Sleepiness Scale (ESS) is one of the most used self-reported instruments to assess sleepiness. Thus, several adaptations into different Languages have been performed worldwide over the years. The…

  2. Sleep assessment using EEG-based wearables - A systematic review.

    Sleep Med Rev2024n=60Systematic Review131 influential citations

    Polysomnography (PSG) is the reference standard of sleep measurement, but is burdensome for the participant and labor intensive. Affordable electroencephalography (EEG)-based wearables are easy to use and are gaining popularity, yet…

  3. The effect of alcohol on subsequent sleep in healthy adults: A systematic review and meta-analysis.

    Sleep Med Rev2025n=27meta119 influential citations

    Alcohol is commonly consumed prior to bedtime with the belief that it facilitates sleep. This systematic review and meta-analysis investigated the impact of alcohol on the characteristics of night-time sleep, with the intent to identify…

  4. Reconsidering sleep perception in insomnia: from misperception to mismeasurement.

    J Sleep Res2023Systematic Review96 influential citations

    Summary So‐called ‘sleep misperception’ refers to a phenomenon in which individuals have the impression of sleeping little or not at all despite normal objective measures of sleep. It is unknown whether this subjective–objective mismatch…

  5. Sex Differences in Insomnia and Circadian Rhythm Disorders: A Systematic Review.

    Medicina (Kaunas)2024n=11Systematic Review93 influential citations

    Insomnia and circadian rhythm disorders are increasingly common in modern society and lead to significant challenges for people's health and well-being. Some studies suggests that men and women differ in neurohormonal secretion, biological…

  6. Impact of one night of sleep restriction on sleepiness and cognitive function: A systematic review and meta-analysis.

    Sleep Med Rev2024n=44Meta-Analysis79 influential citations

    Detrimental consequences of chronic sleep restriction on cognitive function are well established in the literature. However, effects of a single night of sleep restriction remain equivocal. Therefore, we synthesized data from 44 studies to…

  7. Systematic review: REM sleep, dysphoric dreams and nightmares as transdiagnostic features of psychiatric disorders with emotion dysregulation - Clinical implications.

    Sleep Med2025n=28Systematic Review72 influential citations

    <h4>Background</h4>Fragmented rapid eye movement (REM) sleep disrupts the overnight resolution of emotional distress, a process crucial for emotion regulation. Emotion dysregulation, which is common across psychiatric disorders, is often…

  8. A systematic review of the performance of actigraphy in measuring sleep stages.

    J Sleep Res2024n=100Systematic Review70 influential citations

    The accuracy of actigraphy for sleep staging is assumed to be poor, but examination is limited. This systematic review aimed to assess the performance of actigraphy in sleep stage classification of adults. A systematic search was performed…

  9. Effect of time of day on outcomes in elective surgery: a systematic review.

    Anaesthesia2024n=798,914Systematic Review64 influential citations

    <h4>Background</h4>The timing of elective surgery could affect clinical outcome because of diurnal rhythms of patient physiology as well as surgical team performance. Waiting times for elective surgery are increasing in many countries,…

  10. Circadian alignment of food intake and glycaemic control by time-restricted eating: A systematic review and meta-analysis.

    Rev Endocr Metab Disord2024n=116Meta-Analysis59 influential citations

    Daily rhythms of metabolic function are supported by molecular circadian clock systems that are strongly regulated by feeding and fasting. Intermittent fasting diets have been associated with weight loss and improved metabolism. However,…

Frequently asked

What dosage was studied?
• Epworth Sleepiness Scale (ESS) • EEG-based wearables for sleep measurement (Not reported) • Alcohol consumed prior to bedtime (Low dose ≤0.50 g/kg (~2 standard drinks) and high dose ≥0.85 g/kg (~5 standard drinks))
Which population does the evidence apply to?
Most studies investigated: unknown.
Are there safety considerations for Sleep Cycles?
• No adverse events reported in the abstract. • High doses were about five standard drinks (≥0.85 g/kg). • Even low doses (≤0.50 g/kg) disrupted REM sleep. • not reported

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