Personal light exposure patterns and incidence of type 2 diabetes: analysis of 13 million hours of light sensor data and 670,000 person-years of prospective observation

Authors: Daniel P. Windred, Angus C. Burns, Martin K. Rutter, Chris Ho Ching Yeung, Jacqueline M. Lane, Qian Xiao, Richa Saxena, Sean W. Cain, Andrew J. K. Phillips

Year: 2024

Category: Epidemiology

Journal: Lancet

Institution: UK Biobank

DOI: 10.1016/j.lanepe.2024.100943

URL: https://www.thelancet.com/pdfs/journals/lanepe/PIIS2666-7762(24)00110-8.pdf

Abstract

Overview

Exposure to light at night has been shown to disrupt circadian rhythms, and such circadian disruption is a recognized risk factor for type 2 diabetes. However, there has not previously been a large-scale prospective cohort study to directly assess whether personal light exposure patterns predict the development of type 2 diabetes. This study evaluates the relationship between personal light exposure patterns and incident type 2 diabetes using approximately 13 million hours of light sensor data from UK Biobank participants.

Methods

  • Sample: 84,790 participants (mean age 62.3 ± 7.9 years; 58% female).
  • Participants wore light sensors for one week, recording day and night exposure.
  • Researchers modeled circadian amplitude and phase using weekly light data.
  • Incident type 2 diabetes (1,997 cases) was tracked over a mean follow-up of 7.9 ± 1.2 years, excluding pre-existing diabetes cases.
  • Multivariable analysis controlled for age, sex, ethnicity, socioeconomic and lifestyle factors, and polygenic risk.

Findings

  • Higher diabetes risk was observed among individuals exposed to brighter night light, compared to those with darker night environments.
  • Risk was incrementally higher across brighter night light exposure percentiles:
    • 50-70th percentile: HR = 1.29 [1.14-1.46]
    • 70-90th percentile: HR = 1.39 [1.24-1.57]
    • 90-100th percentile: HR = 1.53 [1.32-1.77]
  • Lower circadian amplitude and early/late circadian phase were both linked to higher diabetes risk.
  • Night light exposure and polygenic risk acted as independent risk predictors.
  • The increase in diabetes risk from bright night light was comparable to the risk associated with moderate genetic predisposition.

Conclusion

  • Exposure to bright night light, as well as disrupted circadian rhythms (often caused by irregular light patterns), significantly increases the risk of developing type 2 diabetes.
  • Avoiding light at night could serve as a straightforward and cost-effective preventative recommendation for diabetes, irrespective of genetic risk—a particularly relevant finding for EMF and light safety guidelines.
light exposure circadian rhythms type 2 diabetes night light epidemiology EMF safety prospective cohort
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