High night-to-night variability in ambient temperature is associated with increased sleep timing irregularity

Bastien Lechat; Daniel P. Windred; Kelly Sansom; Hannah Scott; Josh Fitton; Andrew J.K. Phillips; Pierre Escourrou; Amy C. Reynolds; Danny J. Eckert

doi:10.1016/j.sleh.2025.12.001

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High night-to-night variability in ambient temperature is associated with increased sleep timing irregularity

Journal article

Open access

Peer reviewed

High night-to-night variability in ambient temperature is associated with increased sleep timing irregularity

Bastien Lechat, Daniel P. Windred, Kelly Sansom, Hannah Scott, Josh Fitton, Andrew J.K. Phillips, Pierre Escourrou, Amy C. Reynolds and Danny J. Eckert

Sleep health, Vol.12(2), pp.205-213

2026

DOI: https://doi.org/10.1016/j.sleh.2025.12.001

PMID: 41558876

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Abstract

Big data

Climate change

Environmental stress

Heat

Sleep regularity

Wearables

Objectives Daily temperature variability is projected to increase in some world regions up to 100% by 2100. This study investigated associations between night-to-night temperature variability with sleep duration timing and regularity. Methods Data were collected from global users of the Withings Sleep Analyzer (n = 125,295) and ScanWatch (n = 238,550) between January 2020-September 2023. Sleep regularity was assessed using intra-monthly variation in sleep duration and timing (onset, midpoint and offset). Ambient temperature data were extracted from established climate models to calculate night-to-night temperature variability. Fixed-effects models were used to assess the association between night-to-night temperature variability and sleep regularity (duration and timing). Results Participants (n = 313,822) were middle-aged (50 ± 15 years), 70% male, with an average 17 months of data. During months with high vs. low night-to-night temperature variability (99th percentile: 4.3°C vs. 50th percentile: 1.9°C), sleep onset variability was higher in southern (mean [95%CI]; 17.9 [16.1, 19.6]min), central (6.5°C vs. 1.0°C; 32.2 [29.8, 34.6]min) and northern locations (5.5°C vs. 2.1°C; 11.4 [11.2, 11.7]min). There was greater variability in sleep midpoint and offset with higher night-to-night temperature variability, with similar effect sizes. High night-to-night temperature variability was associated with <10 minutes difference in sleep duration irregularity. Conclusions Our findings highlight that high night-to-night temperature variability is associated with a 20%-50% increase in sleep timing irregularity, with central and southern regions being more affected. Given that sleep irregularity is associated with adverse health outcomes, targeted interventions to mitigate the impact of temperature variability on sleep health is an important public health priority.

Details

Title: High night-to-night variability in ambient temperature is associated with increased sleep timing irregularity
Authors/Creators: Bastien Lechat - Adelaide Institute for Sleep Health
Daniel P. Windred - Adelaide Institute for Sleep Health
Kelly Sansom - Adelaide Institute for Sleep Health
Hannah Scott - Adelaide Institute for Sleep Health
Josh Fitton - Adelaide Institute for Sleep Health
Andrew J.K. Phillips - Adelaide Institute for Sleep Health
Pierre Escourrou - Learning Planet Institute
Amy C. Reynolds - Adelaide Institute for Sleep Health
Danny J. Eckert - Adelaide Institute for Sleep Health
Publication Details: Sleep health, Vol.12(2), pp.205-213
Number of pages: 9
Grant note: 1196261; 2025886 / National Health and Medical Research Council (http://data.elsevier.com/vocabulary/SciValFunders/501100000925)
Identifiers: 991005884946007891
Murdoch Affiliation: Centre for Healthy Ageing
Language: English
Resource Type: Journal article

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