Research

Hormonal

There is no consistent causal evidence that higher BMI or Type 2 Diabetes causes changes in chronotype or sleep duration, nor that chronotype or sleep duration causally affect BMI or Type 2 Diabetes, despite observed genetic correlations.

While poor sleep and obesity are linked, this study suggests that one does not necessarily cause the other. You may need to address both sleep hygiene and metabolic health independently, as they might share common genetic roots rather than a direct cause-and-effect relationship.

GoodRefutesHIGH confidence
Mendelian Randomisation analyses, with limited power, provided no consistent evidence of causal associations between BMI or type 2 diabetes and chronotype or sleep duration.
Samuel E. Jones et al. · PLoS Genetics · 2016

Why this rating

Large sample size (UK Biobank) and robust statistical method (Mendelian Randomization), though the authors note 'limited power' due to the small effect sizes of the genetic instruments.

Source

Genome-Wide Association Analyses in 128,266 Individuals Identifies New Morningness and Sleep Duration Loci

Samuel E. Jones et al. · PLoS Genetics · 2016

DOI 10.1371/journal.pgen.1006125

cohort · n=128266Cited 411×
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DOI resolved against Crossref · corpus check 2026-06-10

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