Is 24-hour lighting putting us on a path to depression?

By DAILY MAIL REPORTER
Updated:


BUCHANAN STREET GLASGOW.

Bright lights may affect your mental health

Bright street lighting and office blocks that remain lit all night could be affecting our mental health, scientists have warned.

Researchers said too much light at night can be linked to depression.

Those living in cities have long complained that fluorescent street lights affect their ability to sleep and can alter their mood.

Now psychologists have confirmed that being unable to escape to the dark can have a harmful effect on someone's personality.

In tests on mice, the study authors found that those kept in a lit room 24 hours a day showed more depressive symptoms than those that had a normal light-dark cycle.

Mice that lived in constant light, but could escape into a dark tube when they wanted showed less evidence of depressive symptoms than those who had no escape.

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Laura Fonken, who led the study at Ohio State University in the U.S., said: 'The ability to escape light seemed to quell the depressive effects. But constant light with no chance of escape increased depressive symptoms.'

Co-author Professor Randy Nelson said the results suggested more attention needed to be focused on how artificial lighting affects emotional health in people.

He said: 'The increasing rate of depressive disorders in humans corresponds with the increasing use of light at night in modern society.

'Many people are now exposed to unnatural light cycles, and that may have real consequences for our health.'

The study, published in the journal Behavioural Brain Research, involved 24 male laboratory mice.

Half were housed in light for 16 hours a day and darkness for eight hours, while the other half had 24 hours of light.

Half of each group had dark tubes in their units that let them escape the light when they chose.

The other half had similar tubes that were clear and let light in. After three weeks, the mice began a series of tests that are used to measure depression and anxiety in animals.

In all the tests, mice living in constant light showed more depressive-like symptoms than those with normal light- dark cycles.

Miss Fonken said the results provide additional evidence that the use of artificial light at night may have harmful effects on health in humans.

She said: 'This is important for people who work night shifts, and for children and others who watch TV late into the night, disrupting their usual light-dark cycle.'

The researchers pointed out that many hospital wards are brightly lit all night, which may add to the problems of in-patients.

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