nEWS rELEASE
June 2, 2014

Penn Medicine Research Reveals Suicides Are Far More Likely to Occur After Midnight

PHILADELPHIA — A new study by researchers at Penn Medicine is the first to reveal that suicides are far more likely to occur between midnight and 4 a.m. than during the daytime or evening. The research abstract was published recently in an online supplement of the journal Sleep and will be presented at SLEEP 2014, the 28th annual meeting of the Associated Professional Sleep Societies LLC.

“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, PhD, associate professor in the Department of Psychiatry and Director of the Penn Behavioral Sleep Medicine Program at Penn. “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 said.

For the study, the researchers analyzed data from National Violent Death Reporting System, which provided data for the estimated time of fatal injury, and the American Time Use Survey, which provided an hourly proportion of the American population that is awake. A total of 35,332 suicides were included in the analysis.

Results show that the weighted, scaled mean suicide rate per hour was 10.27 percent after midnight, peaking at 16.27 percent between 2 a.m. and 2:59 a.m.  In contrast, the mean suicide rate per hour was 2.13 percent between 6 a.m. and 11:59 p.m.  When six-hour time blocks were examined, the observed frequency of suicide between midnight and 5:59 a.m. was 3.6 times higher than expected.

According to the authors, previous research suggesting that more suicides occur during the day failed to account for the proportion of the population that is awake at each given hour.  Perlis notes that an important implication of the study is that the treatment of insomnia may be one way to reduce suicide risk.

Other Penn authors on the study include: Michael A. Grandner, PhD, Gregory K. Brown, PhD, Mathias Basner, MD, PhD, MSc, Subhajit Chakravorty, MD, Knashawn H. Morales, ScD Michael E. Thase, MD, David F. Dinges, PhD, Phillip R. Gehrman, PhD, and Ninad S. Chaudhary.

For more information, please see the AASM press release.

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Penn Medicine is one of the world's leading academic medical centers, dedicated to the related missions of medical education, biomedical research, and excellence in patient care. Penn Medicine consists of the Raymond and Ruth Perelman School of Medicine at the University of Pennsylvania (founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System, which together form a $4.3 billion enterprise.

The Perelman School of Medicine has been ranked among the top five medical schools in the United States for the past 17 years, according to U.S. News & World Report's survey of research-oriented medical schools. The School is consistently among the nation's top recipients of funding from the National Institutes of Health, with $392 million awarded in the 2013 fiscal year.

The University of Pennsylvania Health System's patient care facilities include: The Hospital of the University of Pennsylvania -- recognized as one of the nation's top "Honor Roll" hospitals by U.S. News & World Report; Penn Presbyterian Medical Center; Chester County Hospital; Penn Wissahickon Hospice; and Pennsylvania Hospital -- the nation's first hospital, founded in 1751. Additional affiliated inpatient care facilities and services throughout the Philadelphia region include Chestnut Hill Hospital and Good Shepherd Penn Partners, a partnership between Good Shepherd Rehabilitation Network and Penn Medicine.

Penn Medicine is committed to improving lives and health through a variety of community-based programs and activities. In fiscal year 2013, Penn Medicine provided $814 million to benefit our community.

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