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

Area of Science:

• Environmental Health
• Sleep Science
• Climate Change Impact

Background:

• Global temperatures are rising, with projections indicating significant increases in daily temperature variability by 2100.
• Sleep regularity is crucial for overall health, and its disruption can have adverse consequences.

Purpose of the Study:

• To investigate the association between night-to-night temperature variability and sleep duration timing and regularity.
• To identify geographical regions most affected by temperature variability's impact on sleep.

Main Methods:

• Utilized sleep data from over 313,000 global users of Withings Sleep Analyzer and ScanWatch devices (2020-2023).
• Assessed sleep regularity through intra-monthly variations in sleep duration, onset, midpoint, and offset.
• Calculated night-to-night temperature variability using climate models and analyzed associations with fixed-effects models.

Main Results:

• High night-to-night temperature variability (99th percentile: 4.3°C) was linked to increased sleep onset variability across all regions compared to low variability (50th percentile: 1.9°C).
• Central and southern regions exhibited greater sleep onset variability (32.2 min and 17.9 min, respectively) under high temperature variability.
• While sleep duration irregularity showed minimal change (<10 min), sleep timing (onset, midpoint, offset) demonstrated significant irregularity.

Conclusions:

• High night-to-night temperature variability significantly increases sleep timing irregularity by 20%-50%, particularly impacting central and southern regions.
• Sleep timing irregularity is linked to adverse health outcomes, highlighting the need for public health strategies.
• Mitigating the impact of temperature variability on sleep health is a critical public health priority.