A new study indicates suicides are most
likely to happen between midnight and 4 a.m. than any other time of the day.
University of Pennsylvania researchers
based their study on data on the estimated time of fatal injury, supplied by
the National Violent Death Reporting System, and data on hourly proportion of
the American population that is awake, provided by the American Time Use
Survey. They studied over 35,332 suicide cases and classified them into
one-hour slots. Then, they made a comparison between these data and the data on
the number of people who stay awake during a particular time slot.
The study findings reveal that the rate
of suicide per hour was 10.27 percent after midnight with it reaching its peak
at 16.27 percent between 2 a.m. and 2.59 a.m.
On the other hand, the rate of suicide per hour was 2.13 percent between
6 a.m. and 11:59 p.m. When 6-hour time
slots were observed, the suicide frequency between midnight and 5:59 a.m. was
3.6 times higher than anticipated.
The study has brought into focus
the sad fact that in America, the number of suicides (38,000) far exceeds the
number of lives that succumb to homicide (16,000) each year.
The study authors assert that their study
results belie the previous research results, which indicated that more suicides
occur during the day since the previous study failed to take into account the
proportion of population that is awake at each given hour in the night.
The researchers believe that the study
results may bring to light factors that could trigger suicide.
"This appears to be the first
data to suggest that circadian factors may contribute to suicidality and help
explain why insomnia is also a risk factor for suicidal ideation and behavior,"
said principal investigator Michael Perlis, Ph.D., associate professor
in the Department of Psychiatry and Director, Penn Behavior Sleep Medicine
Program at the University of Pennsylvania in Philadelphia.
"These results suggest that not only
are nightmares and
insomnia significant risk factors for suicidal ideation and behavior, but just
being awake at night may in and of itself be a risk factor for suicide," he
Perlis also observed that an important
fallout of the study is that treating insomnia may have a positive impact on
The American Academy of Sleep Medicine
has determined that about 10 percent of adults in the US suffer from chronic
insomnia that lasts for at least 3 months.
Also, with increasing number of veteran suicides posing a
challenge and with 20 percent of veterans suffering from sleep apnea, the
Veterans Health Administration recently introduced a program that applies
cognitive behavioral therapy to treat insomnia and post-traumatic stress
disorder, its accompaniment, in veterans.
"This is one of the times when we identified a problem and the
solution is already en route," Perlis said.
An abstract of the study was published in
the journal Sleep
, and the findings
were presented at SLEEP2014, the 28th annual meeting of the Associated
Professional Sleep Societies LLC on Tuesday June 3, in Minneapolis, Minnesota.