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Higher overall pre-sleep artificial light at night intensity is associated with shorter total sleep time in shift-working nurses and daytime office workers

This observational study of 136 shift nurses and 66 daytime office workers found that higher overall pre-sleep light intensity (Light PC1) measured by wrist actigraphy was strongly associated with shorter total sleep time (β=-0.59, SE=0.08, p<0.001). Bedroom light intensity showed a weaker but significant association with shorter total sleep time (β=-0.21, SE=0.09, p=0.028). Temporal patterns of light exposure (Light PC2) were not significantly associated with any sleep outcomes.

Last updated: Aug 12, 2026•0 RCTs•📖 Read as article →

Evidence Score

Evidence Score34/100
Human RCT☆☆☆☆☆
Meta-analysis☆☆☆☆☆
Mechanism★★★★★
Safety★★★★☆
Confidencelow

Study Evidence

Study 1. Principal component analysis of pre-sleep artificial light at night exposure patterns and the associations with sleep disturbances in Hong Kong shift-working nurses and daytime office workers.

observational

Li B, Liu Y, Li W, Ma JYT, Huss A, Chan J, Wing YK, Tse LA · Occupational and environmental medicine (2026)

Participants: N/A
Duration: 7 days
Intervention: Pre-sleep artificial light at night exposure (observational, no intervention)
Outcome: Total sleep time (TST), sleep onset latency, wake after sleep onset (WASO), sleep timing
Effect Size: β=-0.59 (SE=0.08) for wrist-worn Light PC1 on TST
Population: Hong Kong shift-working nurses (n=136) and daytime office workers (n=66)

Result:

PubMed: 42532831DOI: 10.1136/oemed-2026-111078

Mechanism Graph

Pre-sleep light exposure suppresses melatonin secretion
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Melatonin suppression delays circadian rhythm
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Delayed circadian rhythm shortens sleep duration
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Result: Shorter total sleep time

Limitations

  • ⚠Observational study design, cannot establish causality
  • ⚠Actigraphy-based light measurement may not fully capture all light properties (e.g., wavelength, spectrum)
  • ⚠Potential residual confounding from sociodemographic and work-related factors

Frequently Asked Questions

What is the main finding of this study?▼

Higher overall pre-sleep light intensity is associated with shorter total sleep time, with a stronger effect for wrist-worn light than bedroom light.

Does the temporal pattern of light exposure matter?▼

No, the temporal pattern (Light PC2) was not significantly associated with any sleep outcomes in this study.

Who were the participants?▼

The study included 136 shift-working nurses and 66 daytime office workers in Hong Kong, with data collected from July 2022 to February 2023.

What sleep parameters were measured?▼

Total sleep time, sleep onset latency, wake after sleep onset, and sleep timing were measured using actigraphy.

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References

  1. 1.Li B, Liu Y, Li W, Ma JYT, Huss A, Chan J, Wing YK, Tse LA. "Principal component analysis of pre-sleep artificial light at night exposure patterns and the associations with sleep disturbances in Hong Kong shift-working nurses and daytime office workers.." Occupational and environmental medicine, 2026. PMID: 42532831 DOI: 10.1136/oemed-2026-111078
Disclaimer: This content is for educational purposes only and is not medical advice. Evidence scores reflect the quality and quantity of available research, not clinical recommendations. Always consult a healthcare professional before starting any supplement or intervention.