Bright lights, big danger?
People exposed to bright light between 12:30 and 6 a.m. are at greater risk of developing Type 2 diabetes, regardless of how much light they are exposed to during the day, new research suggests.
“We found that exposure to brighter light at night was associated with a higher risk of developing Type 2 diabetes,” senior study author Andrew Phillips, an associate professor at Flinders University in Australia, said in a statement.
The findings, published this month in the Lancet Regional Health—Europe, relied on data from about 85,000 study participants. A wrist sensor, worn for one week, monitored their light exposure throughout the day.
Researchers collected 13 million hours of light sensor information and tracked participants for nine years to observe whether or not they developed Type 2 diabetes.
Type 2 diabetes is a chronic condition that occurs when your body doesn’t produce enough insulin or doesn’t use insulin well. Obesity, poor diet and inactivity are major risk factors.
According to the Centers for Disease Control and Prevention, more than 38 million Americans have diabetes (about 1 in 10) — and some 90% to 95% of them have Type 2 diabetes. And that number is projected to skyrocket in the coming years.
In relationship to light, researchers explain that nighttime exposure can disrupt the body’s 24-hour biological clock, leading to changes in insulin secretion and glucose metabolization.
“Changes in insulin secretion and glucose metabolism caused by disrupted circadian rhythms affect the body’s ability to regulate blood sugar levels, which can ultimately lead to the development of Type 2 diabetes,” Phillips said.
These findings echo evidence of a link between poor sleep quality and the development of Type 2 diabetes.
Accounting for other factors, including sleep patterns, diet and mental health, researchers found that more exposure to light at night was still a strong predictor of diabetes.
“The results showed that exposure to brighter light at night is associated with a higher risk of developing diabetes, with a dose-dependent relationship between light exposure and risk,” Phillips said.
On the bright side, these findings suggest that reducing light exposure in the evening and maintaining a dark environment could be a cheap and easy way to prevent or delay the development of diabetes, even for those who are high risk.