Are "Night Owls" More Prone to Depression?

By Paul Gaita 02/13/19

Researchers examined if burning the midnight oil could put you at higher risk for mental health disorders.

a woman who is a night owl working late

New research has found that a genetic link may exist between individuals who prefer sleeping later, or "night owls," and mental disorders, including depression, anxiety and even schizophrenia.

A study of genomic data—information culled from an organism's genetic and DNA material—from thousands of participants in a UK health survey found that while differences in sleep timing did not impact sleep quality of "night owls" or "morning people," it did reveal a causal link between night owls and the aforementioned conditions.

While the reason for the connection remained unclear, researchers indicated that its presence underscored the need for greater research into genetics and mental health.

The study, published in the journal Nature Communications, reviewed genomic data from nearly 700,000 participants culled from two sources: the private, U.S.-based genome analysis company 23andMe and the non-profit UK Biobank.

Participants were given a health survey in which they would answer if they were "morning people" or "night owls" based on sleep timing and tendencies. The researchers compared information from the survey with data from wristband activity trackers worn by 85,000 participants in the UK Biobank.

The data yielded two significant findings. First, the researchers determined a vastly larger number of regions in the human genome—351—associated with early rising than previously identified; prior to the study, only 24 of these regions were known to science. Study participants with more gene variants connected to early rising typically went to sleep up to a half hour earlier than individuals with fewer variants.

These variants also appeared to be linked to both the retina and the body's circadian clock, which is the body's means of monitoring sleep, wakefulness, digestion and other bodily functions.

As study lead author Samuel Jones noted, "Part of the reason why some people are up with the larks while others are night owls is because of differences in both the way our brains react to external light signals and the normal functioning of our internal clocks."

But what the scientists also found was that those individuals whose genomic data identified them as night owls also had a greater propensity for the risk of depression and schizophrenia, among other conditions.

Sleep quality or lack of sleep did not appear to play a role in this causal link, and while the researchers were unable to determine a specific reason for the link, study co-author Jacqueline Lane suggested that a combination of physical stimuli, such as morning light, societal pressures—the need to feel awake in the morning and midday due to work schedules—and genetics may play a role.

"Our current study really highlights the need for further study of how chronotype is causally linked to mental health and, until these studies are done, we can only speculate on the mechanism," said Lane.

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Paul Gaita lives in Los Angeles. He has contributed to the Los Angeles Times, Variety, LA Weekly, and The Los Angeles Beat, among many other publications and websites.