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Suicides are more likely late at night, researchers find

(istockphoto) (istockphoto)

It seems that everything gets worse at night — especially the blues.

There’s now evidence that it isn't just you or pseudo-scientific folklore: people who are awake in the middle of the night are three to six times more likely to commit suicide, according to a forthcoming research paper.

The study by University of Pennsylvania researchers is the first to look at  whether the time of day affects the prevalence of suicide among people who are actually awake at those times.

The results were striking, according to lead researcher Michael Perlis, an associate professor of psychiatry at the University of Pennsylvania.

“It appears that suicide prevalence is three to six times greater during the night,” Perlis said. “But that outside of that zone, what time of day has no predictive value whatsoever — it’s all the same.”

“Time of day is only relevant when it comes to the night,” he added.

Whether the cause is insomnia, nightmares or depression that leaves its sufferers awake well into the night, Perlis said that the human body is programmed to turn off the part of the brain that is critical to decision making — the frontal cortex — at night, which makes impulse control more difficult.

Add the known relationship between insomnia or nightmares and suicidal ideation, as well as the absence of social support and restraints and you have a perfect storm.

“If you are awake when reason sleeps, you are at risk,” Perlis explained. “And that is true for every person on this planet. We’re not biologically prepared, most of us, to be awake from 11 [p.m.] to 7 [a.m.].”

“This is a time when we are pre-programmed to go offline and there’s nowhere that goes more offline than your frontal lobe,” he added.

A previous study of suicide in Italy in 1987 hypothesized that suicide was more likely during the day. A 1991 study of suicide in Sacramento and another 1996 study of suicide in Italy made similar findings.

But none of those analyses took into consideration that at night, most people are asleep.

“One thing that is an absolute requirement for any behavior is that you’re awake,” Perlis said.

A clear pattern emerged when he looked at the prevalence of suicide among the people were actually awake at a particular time of day.

The data comes from a very large dataset from the Centers for Disease Control, which documents suicides and the time they were attempted in 18 states. The data includes more than 35,000 suicides.

The study's results will be presented at the annual conference of the Associated Professional Sleep Societies.

The findings are added evidence that treatment for sleep disorders can have a positive impact on mortality, Perlis said.

“If we could just get people to sleep through the night, and they would live, that would be great,” he said.

With growing problems like the rate of suicide among veterans, sleep has already become a growing focus. Twenty percent of veterans suffer from sleep apnea,  compared to just 5 percent of other Americans, according to the Department of Veterans Affairs.

With that in mind, the Veterans Health Administration recently began rolling out a program to use cognitive behavioral therapy to treat veterans for insomnia and post-traumatic stress disorder, which often accompanies it.

“This is one of the times when we identified a problem and the solution is already en route,” Perlis said.

Abby Phillip is a national political reporter for the Washington Post. She can be reached at On Twitter: @abbydphillip

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