ArticleJournal of sleep research2017
Sex and ancestry determine the free-running circadian period.
Article in Journal of sleep research, 2017. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 28 papers, 1 of them a synthesis that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
28 citing papers in PubMed, 1 synthesis or guideline pooled it, 46 citations in OpenAlex.
- Disrupting the clock: meta-analysis of irregular night shifts and migraine, proposing shift work migraine disorder with chronobiology strategies.Frontiers in neurology · 2025Pooled it
- Trial
- Photic Cycle Shorter Than or Equal to Endogenous tau Postpones Diet-Induced Obesity in Mice and Shows a Robust Aftereffect.FASEB journal : official publication of the Federation of American Societies for Experimental Biology · 2026Article
- Late evening room light and sleep restriction reduces the ability of bright morning light to phase advance adolescents' circadian clocks.Scientific reports · 2026Article
- Sexual Dimorphism in Cardiometabolic Diseases: From Development to Senescence and Therapeutic Approaches.Cells · 2025Review
- Unveiling Coronasomnia: Pandemic Stress and Sleep Problems During the COVID-19 Outbreak.Nature and science of sleep · 2024Review
- Desynchronizing the sleep---wake cycle from circadian timing to assess their separate contributions to physiology and behaviour and to estimate intrinsic circadian period.Nature protocols · 2023Review
- Stories from a life studying circadian rhythms and sleep.Sleep advances : a journal of the Sleep Research Society · 2023Article
- Sleep and circadian rhythm characteristics in individuals from the general population during the French COVID-19 full lockdown.Journal of sleep research · 2022Article
- The Role of Race, Sex, and Age in Circadian Disruption and Metabolic Disorders.Gastro hep advances · 2022Review
- Review
- Demographic characteristics associated with circadian rest-activity rhythm patterns: a cross-sectional study.The international journal of behavioral nutrition and physical activity · 2021Article
- Circadian Effects of Drug Responses.Annual review of biomedical engineering · 2021Article
- Sex Differences in Circadian Clock Genes and Myocardial Infarction Susceptibility.Journal of cardiovascular development and disease · 2021Article
- An Optimal Time for Treatment-Predicting Circadian Time by Machine Learning and Mathematical Modelling.Cancers · 2020Review
- Novel Approaches for Assessing Circadian Rhythmicity in Humans: A Review.Journal of biological rhythms · 2020Review
- Sex and race influence objective and self-report sleep and circadian measures in emerging adults independently of risk for bipolar spectrum disorder.Scientific reports · 2020Article
- Genetics of the human circadian clock and sleep homeostat.Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology · 2020Review
- Sex Moderates Relationships Among School Night Sleep Duration, Social Jetlag, and Depressive Symptoms in Adolescents.Journal of biological rhythms · 2019Article
- At the Interface of Lifestyle, Behavior, and Circadian Rhythms: Metabolic Implications.Frontiers in nutrition · 2019Review
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
3 authors at 2 institutions in 1 country.
Funding
Abstract
The endogenous, free-running circadian period (τ) determines the phase relationship that an organism assumes when entrained to the 24-h day. We found a shorter circadian period in African Americans compared to non-Hispanic European Americans (24.07 versus 24.33 h). We speculate that a short circadian period, closer to 24 h, was advantageous to humans living around the equator, but when humans migrated North out of Africa, where the photoperiod changes with seasons, natural selection favoured people with longer circadian periods. Recently, in evolutionary terms, immigrants came from Europe and Africa to America ('the New World'). The Europeans were descendents of people who had lived in Europe for thousands of years with changing photoperiods (and presumably longer periods), whereas Africans had ancestors who had always lived around the equator (with shorter periods). It may have been advantageous to have a longer circadian period while living in Europe early in the evolution of humans. In our modern world, however, it is better to have a shorter period, because it helps make our circadian rhythms earlier, which is adaptive in our early-bird-dominated society. European American women had a shorter circadian period than men (24.24 versus 24.41), but there was no sex difference in African Americans (24.07 for both men and women). We speculate that selection pressures in Europe made men develop a slightly longer period than women to help them track dawn which could be useful for hunters, but less important for women as gatherers.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.