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Sleep regularity as an important component of sleep hygiene: a systematic review
Alexandros Kalkanis, Dierik Lenkens, Paschalis Steiropoulos, Dries Testelmans. Sleep medicine reviews, 2025-11-17
Topic: Brain imaging, connectivity and assessment
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. Limited but directionally uniform evidence indicated higher inflammatory markers and poorer lifestyle indices in irregular sleepers. Prospective biobank data associated low Sleep Regularity Index with smaller hippocampal volume and a 26-53 % increase in dementia risk. Five low-bias cohorts showed 20-88 % higher all-cause mortality for the least regular sleepers, independent of sleep duration and quality. Mechanistic pathways implicated circadian misalignment, autonomic imbalance, and systemic inflammation. Across diverse populations and measurement approaches, unstable sleep timing consistently portends poorer mental, metabolic, vascular, cognitive, and survival outcomes. Because sleep regularity is modifiable and objectively trackable with wearables, schedule stabilization merits elevation to a core public-health recommendation and a priority target for randomized intervention trials.
Key findings
- 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.
- Limited but directionally uniform evidence indicated higher inflammatory markers and poorer lifestyle indices in irregular sleepers.
- Prospective biobank data associated low Sleep Regularity Index with smaller hippocampal volume and a 26-53 % increase in dementia risk.
- Five low-bias cohorts showed 20-88 % higher all-cause mortality for the least regular sleepers, independent of sleep duration and quality.
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Study details
- Study designmeta-analysis
- Evidence strengthHigh
How this study scored 71/100
Published in a peer-reviewed journal, and it is a meta-analysis pooling many studies. Scored zero for sample size, effect reported and studied in people because the record does not state it. We have no data on journal's citation record, times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record, institution's track record, multi-centre collaboration and free to read, so those were left out: it earned 40 of the 56 points we could judge it on, which is 71 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Sleep medicine reviews) |
| Journal's citation record | — / 4 | No journal record from OpenAlex — left out of this score |
| Study design | 12 / 12 | A meta-analysis pooling many studies |
| Strength of evidence | 5 / 5 | Rated “high” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 4 / 5 | 2025 — within 3 year(s) of the newest study here |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | A review of other studies — randomisation is not credited here |
| Times cited | — / 7 | No citation count (not found in OpenAlex) — left out of this score |
| Citations per year | — / 5 | No citation count or no year — left out of this score |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| Still being cited | — / 4 | No yearly citation counts — left out of this score |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | — / 3 | Institutions not listed — left out of this score |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 41259946) |
| Free to read | — / 2 | Access not recorded — left out of this score |
| Points | 40 / 56 | Scored on 10 of 20 parts. We have no data for the rest, so they are left out: 40 of the 56 points we could judge it on is 71 out of 100. |
| Total | 71 / 100 | — |
What each of these 20 components measures, and what this score is not →
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Cite this study APA, Vancouver, BibTeX · download .bib or .ris
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APA 7th
Kalkanis, A., Lenkens, D., Steiropoulos, P., & Testelmans, D. (2025). Sleep regularity as an important component of sleep hygiene: a systematic review. Sleep medicine reviews. https://doi.org/10.1016/j.smrv.2025.102203
Vancouver
Kalkanis A, Lenkens D, Steiropoulos P, Testelmans D. Sleep regularity as an important component of sleep hygiene: a systematic review. Sleep medicine reviews. 2025. doi:10.1016/j.smrv.2025.102203. PMID: 41259946.
BibTeX
@article{kalkanis2025-41259946,
author = {Kalkanis, Alexandros and Lenkens, Dierik and Steiropoulos, Paschalis and Testelmans, Dries},
title = {{Sleep regularity as an important component of sleep hygiene: a systematic review}},
journal = {Sleep medicine reviews},
year = {2025},
doi = {10.1016/j.smrv.2025.102203},
pmid = {41259946},
url = {https://doi.org/10.1016/j.smrv.2025.102203}
}
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