Sleep Duration Associated with Depressive Symptoms

Sleep duration may be related to depression, according to a study of adult twins published in the journal Sleep.

Researchers from the University of Washington examined 1,788 adult twins who self-reported habitual sleep and depressive symptoms. The patients, 894 of which were same-sex twin pairs, were found from the Washington Twin Registry. The scientists used quantitative genetic interaction models to observe genetic, shared environmental, and non-shared environmental influences on the depressive symptoms and sleep duration patterns in patients.

“We were surprised that the heritability of depressive symptoms in twins with very short sleep was nearly twice the heritability in twins sleeping normal amounts of time,” principal investigator Nathaniel F. Watson, MD, MSc, from the University of Washington said in a press release. “Both short and excessively long sleep durations appear to activate genes related to depressive symptoms.”

Results showed that those twins who get about 8.9 hours of sleep per night have a total hereditability of depressive symptoms of 27%. That number increased to 53% among twins who gained about 5 hours of sleep per night, and 49% among patients sleeping 10 hours per night.

Watson believes maximizing sleep for depression patients may increase the effectiveness of treatments like psychotherapy.

“Genetic contributions to depressive symptoms increase at both short and long sleep durations,” the authors wrote.

In a separate study in Sleep of 4,175 non-twin patients between the ages of 11 and 17 years, major depression was correlated with short sleeping duration. In adolescents, the results showed, sleeping 6 or fewer hours per night increased the risk for major depression, which in turn increased the risk for decreased sleep duration among the patients.

“These results are important because they suggest that sleep deprivation may be a precursor for major depression in adolescents, occurring before other symptoms of major depression and additional mood disorders,” principal investigator Robert E. Roberts, PhD, professor of behavioral sciences in the School of Public Health at the University of Texas Health Science Center in Houston, said in another press release.