Exposure to any light during sleep linked to obesity, serious health problems, study finds

    Even dim light can disrupt sleep and increase the risk of serious health problems in older adults, a new study finds.

    “Exposure to lots of light during the sleep period correlated with the higher prevalence of diabetes, obesity and high blood pressure in both older men and women, senior author Phyllis Zee, chief of sleep medicine at Northwestern University’s Feinberg School of Medicine in Chicago”

    A study published earlier this year by Zee and her team examined the role of light in sleep for healthy adults in their 20s. Sleeping for just one night in dim light, such as B. with a TV without sound, increased the blood sugar and heart rate of the young people during the sleep laboratory experiment.

    An elevated heart rate at night has been shown in previous studies to be a risk factor for future heart disease and early death, while higher blood sugar levels are a sign of insulin resistance, which can ultimately lead to type 2 diabetes.

    The faint light penetrated the eyelids and disrupted the young adults’ sleep, although the participants slept with their eyes closed, Zee said. But even that tiny amount of light created a deficit in slow-wave, rapid-eye-movement sleep, the sleep stages when most cell renewal occurs, she said.

    Objective measurements

    The new study, published Wednesday in the journal Sleep, focused on seniors who are already at higher risk for diabetes and cardiovascular disease, said co-author Dr. Minjee Kim, an assistant professor of neurology at Northwestern University Feinberg School of Medicine, in a statement.

    We wanted to see if there was a difference in the incidence of these diseases related to nighttime light exposure, Kim said. Instead of dragging people into a sleep lab, the new study used a real-world setting.

    The researchers gave 552 men and women between the ages of 63 and 84 an actigraph, a small device worn like a wristwatch that measures sleep cycles, average movements and light exposure.

    We actually measured the amount of light the person was exposed to with a sensor on their body and compared that to their sleep and wake activity over a 24-hour period, Zee said.

    What I think is different and remarkable about our study is that by using this method, we have truly objective data. Zee and her team said they were surprised that less than half of the men and women in the study were at least consistently in the dark slept five hours a day.

    More than 53% or so had some light in the room at night, she said. In a secondary analysis, we found that those who had more light at night were also the most likely to have diabetes, obesity or high blood pressure. Additionally, Zee said, people who slept with more light were more likely to go to bed later and wake up later, and we know that late sleepers also tend to have a higher risk of cardiovascular and metabolic disorders.

    What to do

    Strategies for reducing light levels at night include positioning your bed away from windows or using light-blocking blinds. Don’t charge laptops and cell phones in your bedroom, where melatonin-altering blue light can disturb your sleep. If light conditions persist, try a sleep mask to protect your eyes. If you have to get up, don’t turn on the lights unless you have to, Zee advised.

    If you do this, keep them as dark as possible and only light them for short periods of time. Older adults often have to get up at night to use the bathroom because of health problems or side effects of medication, Zee said, advising this age group that turning off all lights could put them at risk of falling. In this case, consider using night lights that are positioned very low to the ground and choose lights that are amber or red in color.

    This spectrum of light has a longer wavelength and is less intrusive and disruptive to our circadian rhythm or body clock than shorter wavelengths such as blue light.

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