Women who wake up early less likely to develop depression, study claims

Lack of exposure to daylight might increase a woman’s risk of depression

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Women who describe themselves as “early risers” are less likely to develop depression, new research claims.

A study of more than 32,000 women published in the Journal of Psychiatric Research found that those who are naturally inclined to wake up early are at a lower risk of the mental illness due to greater daylight exposure.

Researchers at the University of Colorado at Boulder and Brigham and Women’s Hospital in Boston examined the links between mood disorders and chronotype i.e. how early or how late a person synchronizes to the 24 hour day.

These tendencies typically manifest on a scale, ranging from morning larks who like to wake up early and go to sleep early and night owls, who prefer the opposite routine.

Whichever end of the scale you fall under is partly determined by genetics, the study’s authors said, before concluding that those in the former category have a 12 to 27 per cent less chance of developing depression.

The four-year-long study was conducted using the data from 32,470 female nurses, which was extracted from the Nurses’ Health Study survey that nurses complete biannually.

Participants had an average age of 55.

When analysis began in 2009, not one participant had been diagnosed with depression. At the time, 37 per cent described themselves as early risers, 53 per cent said they were intermediate types - meaning they were somewhere in the middle of the scale - and 10 per cent described themselves as evening types, or night owls.

Once the study had finished, Vetter and her team observed 2,581 cases of depression had developed, 290 of whom were in the night owl category.

The study found that those who woke up later were more likely to be depressed, even when other factors likely to put them at risk were accounted for, such as living alone, smoking and being single.

“This tells us that there might be an effect of chronotype on depression risk that is not driven by environmental and lifestyle factors," said lead author Céline Vetter.

"Alternatively, when and how much light you get also influences chronotype, and light exposure also influences depression risk,” she added.

“Disentangling the contribution of light patterns and genetics on the link between chronotype and depression risk is an important next step.”

While the findings suggest that a person's sleeping pattern is an independent risk factor for depression, she clarified that this does not necessarily mean night owls will inevitably develop the illness.

"Yes, chronotype is relevant when it comes to depression but it is a small effect," she pointed out, offering some words of advice to those who are prone to rising and sleeping later:

"Try to get enough sleep, exercise, spend time outdoors, dim the lights at night, and try to get as much light by day as possible.”