Keep Naps Short
If you nap, keep it under 30 to 60 minutes: one way to carry out what the cohort syntheses on napping report, with naps of an hour or more associated with cardiovascular risk and mortality (Sun 2022, which describes the evidence for most meta-analyses as weak or suggestive; Salari 2022; Liu 2015) and Du 2026 reporting that napping under 60 minutes maximised cognitive enhancement (SMD 0.69).
- Loud snoring with witnessed gasping/choking or breathing pauses plus daytime sleepiness (possible obstructive sleep apnea), refer to a clinician
- Difficulty falling or staying asleep at least 3 nights/week for 3+ months with daytime impairment (possible chronic insomnia disorder), refer to a clinician
- Excessive daytime sleepiness despite adequate time in bed, or falling asleep involuntarily during activities, refer to a clinician
How to do it
What the evidence says
This practice is one way to carry out what the sources on the concept entry (phys.sleep.concept.napping) studied: daytime napping in cohort syntheses, with cardiovascular disease, stroke, coronary heart disease, mortality and cognition as the outcomes. Sun 2022 (umbrella and systematic review) reports long daytime napping of an hour or more a day associated with higher odds of cardiovascular risk factors, cardiovascular disease and mortality, with short napping not significantly associated, and states that the evidence for most meta-analyses was weak or suggestive. Salari 2022 (dose-response meta-analysis, 8 studies, 167,025 adults) reports daytime napping associated with higher coronary heart disease risk, more so for naps of an hour or more (RR 1.34) than under an hour (RR 1.10). Liu 2015 (meta-analysis, 7 studies) reports daytime napping associated with greater all-cause mortality (RR 1.15) but not cardiovascular mortality, and Jin 2021 (dose-response meta-analysis, 8 studies) reports napping associated with stroke in a dose-dependent manner. Du 2026 (umbrella review of 16 meta-analyses) reports that napping under 60 minutes maximised cognitive enhancement (SMD 0.69) while napping over 60 minutes correlated with a 30% higher risk of coronary heart disease, and concludes that limiting naps to 60 minutes or less may optimise benefits while reducing chronic disease risk. These are observational associations, not trial results. The full account, source by source, is on the concept entry this practice links to (phys.sleep.concept.napping).
- “A long nap is more restorative.” In the pooled cohort syntheses, naps of an hour or more track with worse cardiovascular and mortality outcomes, and the cognitive benefit is reported for naps under 60 minutes.
- Do not claim to diagnose, treat, or cure insomnia, sleep apnea, or any sleep disorder
- Do not promise guaranteed, instant, or permanent improvements in sleep
- Do not present these general hygiene techniques as clinical therapy (e.g., CBT-I) or a substitute for medical care
- Agreement
- Direction recorded for 0 of 11 sources; not yet recorded for the rest.
- The claim's outcome
- Outcome not yet recorded
- Certainty
- A source states a certainty rating for 1 outcome.
- How the sources were read
- Some sources are based on abstracts, not full texts.
What each source measured and concluded (11)
- What it measured
- Association of daytime napping with diabetes, metabolic syndrome, cardiovascular disease, CVD risk factors, and mortality
- How it was read
- based on the abstract, not the full text
- What the review says it includes
- Systematic review (with umbrella review and dose-response meta-analyses)
- Studies and participants, as stated
- 11 articles (umbrella review), 97 articles (systematic review)
- What it measured
- All-cause mortality.
- How it measured it
- Medical record/data linkage.
- How it was read
- read in full text
- What the review says it includes
- Systematic review and meta-analysis of 12 prospective cohort studies
- Studies and participants, as stated
- N=1,524,584 participants across 12 studies
- What it measured
- Dose-response relationship between napping duration and multiple health outcomes (cognitive enhancement, fatigue reduction, chronic disease risks).
- How it measured it
- Meta-analyses using effect sizes (SMD, OR) with confidence intervals.
- How it was read
- read in full text
- What it measured
- Association between sleep regularity and mental, cardiometabolic, inflammatory, cognitive, lifestyle, and mortality outcomes
- How it was read
- based on the abstract, not the full text
- What the review says it includes
- Systematic review (narrative synthesis)
- Studies and participants, as stated
- 59 primary studies (from 3140 records; 147 full texts)
- What it measured
- Coronary heart disease (CHD) risk by daytime napping
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and dose-response meta-analysis
- Studies and participants, as stated
- 8 studies; 167,025 adults
- What it measured
- All-cause and cause-specific (CVD, cancer) mortality
- How it was read
- screened only, not extracted
- What it measured
- Cardiovascular and all-cause mortality
- How it was read
- screened only, not extracted
- What the review says it includes
- Meta-analysis of prospective studies
- Studies and participants, as stated
- 7 studies; 98,163 subjects
- What it measured
- Relationship between daytime napping and stroke
- How it was read
- screened only, not extracted
- What the review says it includes
- Dose-response meta-analysis of cohort studies
- Studies and participants, as stated
- 8 studies; 524,408 participants; 5,875 stroke cases
- What it measured
- All-cause mortality
- How it was read
- screened only, not extracted
- What it measured
- Association of sleep duration, regularity, and quality with all-cause and cardiovascular mortality, cardiometabolic syndrome, and coronary artery disease
- How it was read
- screened only, not extracted
- What it measured
- Incidence of chronic diseases
- How it was read
- screened only, not extracted
Certainty ratings the sources state (1)
- Rating, as the source states it
- Moderate
- Framework
- not named by the source
- Applies to
- Moderate-certainty evidence linked greater sleep-timing irregularity to higher depressive/anxiety symptoms, elevated BMI, insulin resistance, hypertension, cardiovascular events; low Sleep Regularity Index associated with 26-53% increased dementia risk and 20-88% higher all-cause mortality
- Stated by
- Kalkanis et al. (2025)
Each source below is shown with its study design and a link to the original study, or, where it is not a completed research paper, with what kind of record it is; those are not counted. This is the audit trail.
Why do some records show a record type instead of a study design?
A study design is shown for a completed, peer-reviewed paper. A registered protocol, a preprint, a conference abstract, a referee report or a book chapter has not been through peer review as a finished paper, so it is labelled for what it is, and it is counted in no source count. Where a record could not be confirmed as a completed paper at all, it says so rather than guessing. They all stay in the list, and their DOI still resolves, because the count of what was screened is part of the audit trail.
- Protocol / registration A registered plan for a review or trial, not its results.
- Preprint Posted by its authors before peer review.
- Conference abstract A conference summary rather than a peer-reviewed paper.
- Peer-review report A referee's report on a paper, not the paper itself.
- Guideline / position stand A recommendation derived from evidence, which is a step further from the data than the evidence itself.
- Book chapter A chapter in a scholarly book rather than a journal paper.
- Type not recorded Our record does not say what kind of publication this is, so it is counted in no source count. That is a gap in our data, not a judgement about the research.
“Abstract only” means the review read that paper’s abstract, not its full text; “screened only” means it was included at re-screening and not extracted. Both stay in the trail with their DOI, because how a source was read is part of the audit.