Latest research illuminates the dangers of light exposure late at night

As bedtime approaches, many of us tend to dim the lights around the house in preparation for a good night’s sleep. However, according to latest research, those who don’t may face an increased risk of early death

To understand the risk of light exposure late at night, researchers from Flinders University studied 13 million hours of data, collected from light sensors worn by 89,000 people, aged between 40 and 69 years old, finding that exposure to bright nights and dark days is associated with an increased risk of death.

Published in the journal Proceedings of the National Academy of Sciences, the researchers found that those who were exposed to high levels of light at night had a 21–34 per cent increased risk of death, whilst those exposed to high levels of daylight had a 17–34 per cent reduction in their risk of death.

Co-senior author, Associate Professor Andrew Phillips said that light exposure at night disrupts our circadian rhythms by shifting the timing (phase-shift) and weakening the signal (amplitude suppression) of the central circadian ‘pacemaker’ which manages circadian rhythms throughout the body.

“Disruption to the body’s circadian rhythms is linked to the development of metabolic syndrome, diabetes, and obesity and is also strongly implicated in the development of cardiometabolic diseases including myocardial infarction, stroke and hypertension,” Associate Professor Phillips said.

“The observed relationships of night light exposure with mortality risk may be explained by night light disrupting circadian rhythms, leading to adverse cardiometabolic outcomes.

“Our findings clearly show that avoiding night light and seeking daylight may promote optimal health and longevity, and this recommendation is easy, accessible and cost-effective.”

Lead author, Dr Daniel Windred said that the findings demonstrate the importance of maintaining a dark environment across the late night and early morning hours to ensure optimal sleep quality and the health benefits that come with it.

“Protection of lighting environments may be especially important in those at risk for both circadian disruption and mortality, such as in intensive care or aged-care settings,” Dr Windred said.

“Across the general population, avoiding night light and seeking day light may lead to reduction in disease burden, especially cardiometabolic diseases, and may increase longevity.”

IMPORTANT LEGAL INFO This article is of a general nature and FYI only, because it doesn’t take into account your personal health requirements or existing medical conditions. That means it’s not personalised health advice and shouldn’t be relied upon as if it is. Before making a health-related decision, you should work out if the info is appropriate for your situation and get professional medical advice.