Some people have the habit of having some light in the room while sleeping at night. While this seems normal, a study by Northwestern University Feinberg School of Medicine in Chicago has found that light exposure during sleep might increase your risk of developing health issues. The three major health problems cited in the study are obesity, high blood pressure and diabetes.
According to this study published in the journal SLEEP, sleeping with light either dim or bright, is associated with an increased risk of hypertension, diabetes and obesity. This study mainly focused on older adults who are exposed to some kind of light during sleep. This could be light from a night lamp or bulb, smartphone light or street light streaks coming through the window. The researchers from Feinberg School of Medicine found out that even a brief exposure to light during sleep can affect our health. Since older adults already have a potential risk of diabetes and high BP, light exposure during sleep can double up the risk.
For this research, the team tracked sleep schedules and habits of 550 older adults aged between 63-84 years. The team specifically analyzed light exposure during sleep through a wrist-worn device for a brief 7-day period. It was found that half of the participants were used to sleeping with some light. These were found to have 100% higher risk of diabetes, 82% risk of obesity and 74% risk of high blood pressure.
Effect of light exposure during sleep on health
While this study was primarily conducted on older adults, previous research has mentioned a link between mistimed light or sleeping with lights on at night with increased heart problems. This might raise heart rate and blood glucose during sleep. Sleep expert Dr. Jonathan Cedernaes from Sweden University backs this claim by mentioning nighttime light exposure adversely affects cardiometabolic health whose ill-effects become evident over time if someone exposes himself/herself to light every night during sleep.
Why does this happen?
As per researchers, light disrupts the circadian rhythm or sleep clock of the body. Light exposure interrupts sleep cycle which impacts bodily functions.When you sleep, the mind signals the body to relax only when there is no light because melatonin hormone is secreted in a dark environment. This is why you easily fall asleep in darkness. Low melatonin levels are linked to increased risk of diabetes and high blood pressure which is why keeping lights on during nighttime sleep might hamper your health.
So, you must avoid light exposure during sleep for good cardiovascular and cardiometabolic health. If really needed, you can keep low bathroom lights on that don't directly reach your eyes. Additionally, you can wear a sleeping mask to block direct light and enjoy a sound sleep and better health.
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