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Study Reveals Sleeping With The Lights On Increases Risk Of Heart Disease & Diabetes

Sleeping with a light on might make it easier to find your way to the loo at 3 am, but it could be bad for your health.

A new study out of the US has revealed that people exposed to artificial light at night show worse glucose and cardiovascular regulation than those who sleep in the dark. The study says it could be due to the body being kept more alert.

“We found that light – even [a] modest amount – increases activation of the autonomic nervous system, which we postulate increased heart rate and decreased insulin sensitivity,” said Dr Phyllis Zee, co-author of the study from Northwestern University Feinberg School of Medicine.

Dr Phyllis Zee and a team studied the glucose tolerance and heart rate of 20 people over two nights. Half spent both nights with dim light, while the other half slept the first night in a room with dim light and the next night in a room with an overhead light equivalent to an overcast day.

While melatonin was similar in both groups, the group that slept a night with the light on had a higher insulin resistance in the morning, higher heart rate and lower heart-rate variability.

“Because we only studied one night and in a healthy group, we are unable to say if these are clinically significant,” said Zee. “However, the change in insulin would be considered a physiologically significant change that may translate into risk for disease.”