Sleep regularity as an important component of sleep hygiene: a systematic review
Abstract
BACKGROUND
Beyond sleep duration and efficiency, the day-to-day regularity of bed- and wake-times is increasingly recognized as a distinct dimension of sleep health. Whether irregular schedules independently predict adverse health outcomes remains unclear.
OBJECTIVE
To synthesize evidence on the association between objectively or diary-quantified sleep regularity and mental, cardiometabolic, inflammatory, cognitive, lifestyle, sleep-disorder, and mortality outcomes in adults.
METHODS
A protocol registered with PROSPERO (CRD420251101936) guided the review. MEDLINE (PubMed), Cochrane Library, PsycINFO, and Google Scholar were searched from inception to July 1, 2025 using a comprehensive strategy incorporating validated regularity metrics (Sleep Regularity Index, interdaily stability, composite phase deviation, social jetlag, night-to-night standard deviations). After duplicate removal, 3140 unique records underwent title/abstract screening; 147 full texts were reviewed. Risk of bias was appraised with the Newcastle-Ottawa Scale. Heterogeneity of metrics and outcomes precluded meta-analysis; evidence was synthesized narratively following SWiM guidelines and graded with van Tulder's best-evidence taxonomy.
RESULTS
Fifty-nine primary studies met all criteria. Consistent, moderate-certainty evidence linked greater sleep-timing irregularity to higher depressive and anxiety symptoms, elevated body mass index, insulin resistance, hypertension, and incident cardiovascular events.…
How strong is the evidence?
Evidence Hub reads this as a systematic review. Its evidence level is 1 of 5 (Highest · pooled evidence). Pooled evidence from several studies sits at the top of the evidence pyramid.
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