Nov 22, 2024 08:00:00

Too much light at night and too little light during the day increase risk of death

Light plays an important role in regulating

the circadian rhythm in the human body, and disruptions to circadian rhythms can lead to a variety of health conditions. Data from more than 88,000 subjects tracking their light exposure for a week showed that people who were exposed to too much light at night or too little light during the day had a higher risk of death.

Brighter nights and darker days predict higher mortality risk: A prospective analysis of personal light exposure in >88,000 individuals | PNAS
https://www.pnas.org/doi/10.1073/pnas.2405924121

Brighter nights and darker days could lead to an early grave – News
https://news.flinders.edu.au/blog/2024/11/01/brighter-nights-and-darker-days-could-lead-to-an-early-grave/

Brighter Nights And Darker Days Can Have a Serious Effect on Mortality Risk : ScienceAlert
https://www.sciencealert.com/brighter-nights-and-darker-days-can-have-a-serious-effect-on-mortality-risk

A research team from Flinders University in Australia analyzed data from UK Biobank , a large biobank in the UK, to investigate how the amount and time of day a person is exposed to light is associated with risk of death.

The data analyzed by the research team included data from 88,905 subjects aged 40 to 69 who wore optical sensors on their wrists for a week, followed by mortality data for eight years.

The analysis found that people who were exposed to high levels of light at night had a 21-34% increased risk of death, while people who were exposed to high levels of sunlight during the day had a 17-34% decreased risk of death. In other words, people who were exposed to too much light at night or too little light during the day had a higher risk of death.

Further analysis using computer modeling showed that disruptions to subjects' circadian rhythms, which are thought to be influenced by the pattern and amount of light exposure, predicted an increased risk of death.

Co-author Professor

Sean Cain , who studies sleep at Flinders University, said: 'Experiencing bright nights and dark days can disrupt our circadian rhythms, which are linked to a range of health problems including diabetes, obesity, cardiovascular disease, mental health issues and increased risk of mortality. These new insights into the potentially harmful effects of light show how important an individual's light exposure patterns are to their health.'

Dr Daniel Windred , lead author of the study, points out that aligning lighting with circadian rhythms may be important for people who are at high risk of both circadian rhythm disruption and mortality, such as those in intensive care units or elderly care facilities.

Co-author Associate Professor Andrew Phillips said: 'Our findings clearly show that avoiding light at night and exposing ourselves to daytime sunlight has the potential to promote optimal health and longevity - it's a simple, cost-effective recommendation.'