Excessive artificial light exposure 'can have negative health consequences'

18 July 2016

Spending too long exposed to artificial lighting could be having a number of negative effects on people's health, according to new research.

Carried out by Leiden University Medical Centre in the Netherlands, the study exposed mice to light around the clock for 24 weeks and measured several major health parameters, demonstrating the health impact of this interruption to the natural light-dark cycle.

Constant light exposure reduced the normal rhythmic patterns in the brain's central circadian pacemaker by 70 per cent, causing a reduction in skeletal muscle function and bone deterioration. The mice also entered a proinflammatory state normally observed only in the presence of pathogens or other harmful stimuli.

However, after the mice were returned to a standard light-dark cycle for two weeks, the animals' circadian rhythm returned to normal, with the corresponding health problems reversed accordingly.

This is an important finding as 75 per cent of the world's population is exposed to light during the night, with constant light exposure common in nursing homes and intensive care units, as well as among people who work into the night.

Johanna Meijer of Leiden University Medical Centre said: "We used to think of light and darkness as harmless or neutral stimuli with respect to health. We now realise this is not the case, based on accumulating studies from laboratories all over the world."

Posted by Edward Bartel


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