Evidence map›Paper›PMID 41067032›Full record

ArticleSleep medicine2025

Associations of latitude and photoperiod with sleep duration in a yearlong study of US physicians.

Katherine Et Ross, Karina Pereira-Lima, Kerby Shedden, Margit Burmeister, Srijan Sen

Abstract read
PubMed Full text at PMC Publisher
In one paragraph

Article in Sleep medicine, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

0numbers the graph read from it
0cells of the map it votes in
1citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

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.

2 · The registry

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.

3 · Its place in the literature

Who cites it

1 citing paper in PubMed.

  1. Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

5 authors.

Katherine Et RossDepartment of Psychology, University of Michigan, Ann Arbor, MI, 48104, USA; Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, 48109, USA. Electronic address: ketross@umich.edu.
Karina Pereira-LimaDepartment of Anesthesiology, University of Michigan, Ann Arbor, USA.
Kerby SheddenDepartment of Statistics, University of Michigan, Ann Arbor, MI, 48109, USA.
Margit BurmeisterMichigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, 48109, USA; Departments of Computational Medicine and Biochemistry, Psychiatry, and Human Genetics, University of Michigan, Ann Arbor, USA.
Srijan SenMichigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, 48109, USA; Eisenberg Family Depression Center, University of Michigan, Ann Arbor, MI, 48109, USA; Michigan Medicine, Department of Psychiatry, Ann Arbor, MI, 48109, USA.

Funding

TRAINING PROGRAM IN DEVELOPMENTAL PSYCHOLOGYT32HD007109 · NICHD · UNIVERSITY OF MICHIGAN AT ANN ARBOR · PI GELMAN, SUSAN A., MONK, CHRISTOPHER STEPHEN · 1985 to 2025
$6.6M
Mobile Technology to Identify Behavorial Mechanisms Linking Genetic Variation and DepressionR01MH101459 · NIMH · UNIVERSITY OF MICHIGAN AT ANN ARBOR · PI SEN, SRIJAN · 2013 to 2023
$6.4M
Multi-Institutional Training in Genetic/Genomic Approaches to Sleep DisordersT32HL110952 · NHLBI · UNIVERSITY OF PENNSYLVANIA · PI CHERVIN, RONALD D, MIGNOT, EMMANUEL J · 2013 to 2022
$5.0M
NHLBI NIH HHS T32 HL110952NICHD NIH HHS T32 HD007109NIMH NIH HHS R01 MH101459
6 · The paper itself

Abstract

Geographic factors may influence sleep, but prior studies have been inconsistent, likely because of reliance on seasonally invariant and self-reported data. Using year-long objective sleep measurements from 4683 U S. medical interns, this study aimed to determine how latitude affects total sleep time (TST) and assess whether photoperiod acts as a mediator in this association. Linear mixed models (LMMs) showed that each 1° increase in latitude was associated with approximately 0.23 min longer TST on average across the year, and daily photoperiod was negatively associated with TST. Simulation-based mediation analyses revealed seasonal effects: in summer, higher latitude led to reduced TST via longer photoperiod, whereas in winter, higher latitude led to increased TST via shorter photoperiod. Direct effects of latitude remained significant during winter, suggesting additional influences beyond photoperiod. These findings indicate that latitude influences TST through a seasonally specific photoperiod-mediated pathway, as well as through other non-photoperiod environmental factors.

Indexed as

PhotoperiodPhysiciansSeasonsSleepAdultFemaleHumansInternship and ResidencyMaleSleep DurationTime FactorsUnited StatesGeographyPhotoperiodSeasonal variationSleepSleep duration

Identifiers

PMID41067032
PMCPMC13322165

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Registered trials

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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.