Light at Night Elevates Risk of Diabetes, Hypertension, Insomnia

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Exposure to relatively bright lights at night can cause a cascade of negative health effects like insomnia, hypertension, diabetes, inflammation, and tumor cell growth, claims a new study. According to researchers, getting too much light at night suppresses melatonin, a hormone the brain’s pineal gland produces in the absence of light. Apart from playing a key role in regulating the body’s biological cycle and lowering blood pressure and body temperature, melatonin also has the potential of limiting insomnia, hypertension, and the development of certain cancers. Lead author of the study, Dr Joshua Gooley of Brigham and Women’s Hospital and Harvard Medical School in Boston stated, “On a daily basis, millions of people choose to keep the lights on prior to bedtime and during the usual hours of sleep. “Our study shows that this exposure to indoor light has a strong suppressive effect on the hormone melatonin. This could, in turn, have effects on sleep quality and the body’s ability to regulate body temperature, blood pressure and glucose levels.”

Study details

In a bid to determine whether exposure to night lights inhibits the production of melatonin, the researchers conducted study. They enrolled 116 healthy volunteers aged 18-30 years for a period of around 10 days. As a part of the study, the study subjects spent five days living in a light-controlled room at Brigham and Women’s Hospital in Boston. They slept for eight hours and were awake for 16 hours each day. In the beginning of the trial, the volunteers were exposed to 16 hours of room light when awake, but later they were exposed to eight hours of room light in the morning and eight hours of dim light in the evening. With the help of intravenous catheters inserted in the arms of study subjects, the investigators measured melatonin levels every 30 to 60 minutes.

Revelations of the study

The researchers noted that when the rooms light was bright, the participants produced melatonin about 90 minutes less each night compared to when the light was dim. In addition, there was a reduction of at least 51 percent in melatonin production when the participants were exposed to room light during sleep hours. The researchers found that “exposure to room light in participants who were kept awake during the usual hours of sleep suppressed melatonin by more than half the amount measured during sleep in darkness.” Dr Gooley added, “Given that chronic light suppression of melatonin has been hypothesised to increase relative risk for some types of cancer and that melatonin receptor genes have been linked to type 2 diabetes, our findings could have important health implications for shift workers.”

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