According to a new study, exposure to light, even low light, can interfere with sleep and increase the risk of serious health problems for older adults.
“Exposure to any amount of light during the sleep period correlated with the higher incidence of diabetes, obesity and high blood pressure in both older men and older women,” says Phyllis Zee till CNN.
She is the director of sleep medicine at Northwestern University Feinberg School of Medicine in Chicago and the lead author of a new study on how exposure to light affects sleep. According to her, people should do their best to minimize the amount of light they are exposed to when they sleep.
Increased heart rate
The new study focuses on the elderly who already have a higher risk than young people of developing diabetes and cardiovascular disease. In a previous study examined Phyllis Zee and her team what role light plays for healthy adults in their 20s and found that a night’s sleep in low light, equivalent to the light from a television, increased blood sugar levels and heart rate in young people.
Previous studies have shown that increased heart rate during sleep increases the risk of future heart disease and premature death. Higher blood sugar levels indicate insulin resistance and may eventually lead to type 2 diabetes.
Study with the elderly
The dim light to which the subjects were exposed in the study’s sleep experiment in the sleeping lab disturbed the young adults’ sleep even though they slept with their eyes closed. The small amount of light caused a deficit of deep sleep and dream sleep, the stages of sleep where most cell renewal takes place.
In the new study where the researchers focused on the elderly, they wanted to see if there was any difference in the frequency of the diseases that are related to light exposure during sleep. In the new study, a sleeping lab was not used, but the subjects slept in their natural environment with a small device that was in a bracelet.
The unit measured the 552 subjects’ sleep cycles, average movements, and their exposure to light.
Phyllis Zee explains that they measured the amount of light the person was exposed to with a sensor on the body and compared it with their sleep and wakefulness during a day.
“What I think is different and remarkable about our study is that we have really objective data with this method,” she told CNN.
Most slept with lights in the room
The researchers were surprised that less than half of the subjects who participated in the study slept in the dark for at least five hours and over 53 percent of them had some light in the room during sleep.
In analyzes, the researchers found that those who were exposed to higher amounts of light during sleep were also more likely to have diabetes, high blood pressure or obesity. Those who slept with more light in the room were also more likely to both go to bed and get up later.
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