Optimizing Darkness in Your Night Environment
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Exposure to light at night significantly raises the risk of heart disease, according to extensive research.
Various environmental and behavioral signals synchronize the body’s circadian rhythms, the internal clocks that manage physiological functions. However, contemporary lifestyles often disrupt these biological mechanisms, heightening sensitivity to health issues.
Light is a primary regulator of circadian rhythms and has been linked to numerous health implications. For instance, shift workers exposed to nighttime light face a higher risk of heart disease.
Previous studies utilizing satellite data have indicated associations between residents of brightly lit urban areas and heart disease, focusing solely on outdoor light at night. Daniel Windred, from Flinders University in Adelaide, and his team sought to determine if overall light exposure impacts cardiovascular health.
They monitored approximately 89,000 individuals without pre-existing cardiovascular conditions, equipping them with light sensors for a week between 2013 and 2016. “This represents the largest research effort on personal light exposure patterns affecting cardiovascular health to date.”
The sensors captured both natural and artificial light sources, including emissions from mobile phones. Over the eight-year period, participants who experienced the brightest nights showed a 23-56% increased risk of developing cardiovascular disease compared to those exposed to darker nights.
For example, individuals in the highest light exposure category included those who activated overhead lights for an hour from midnight to 6 AM. “This scenario places them within the 90th to 100th percentiles of nighttime light exposure,” Windred noted. He emphasized that the body continues to react to artificial light even after it is turned off, and short exposures can disrupt circadian rhythms.
Researchers accounted for factors such as gender, age, smoking habits, and shift work. They also demonstrated that the connection between light exposure and heart disease risk remained constant, regardless of sleep duration, sleep efficiency, or genetic predisposition.
Interestingly, although women generally have a lower incidence of heart disease at the same age as men, exposure to bright nighttime light can neutralize this protective effect due to estrogen. Evidence suggests that women experience more significant melatonin suppression in response to bright light, making their circadian systems more sensitive compared to men.
Disruption of circadian rhythms can compromise glucose tolerance, elevating the risk for type 2 diabetes, which is a risk factor for heart disease. Such disruption also influences blood pressure and can increase the risk for abnormal cardiac rhythms due to conflicting signals between the brain and heart.
“The significance of these findings must not be understated,” stated Martin Young from the University of Alabama at Birmingham. “As a 24/7 society increasingly disrupts our circadian systems, this study underscores the notable health risks linked to such exposure.”
Windred suggests that individuals strive to maintain a darker nighttime environment. “Optimize your sleep schedule to ensure darkness during bedtime. If you awaken during the night, utilize dim lighting and avoid bright overhead lights.”
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Source: www.newscientist.com
