Having any sleep disorder is a risk factor for incident depression, a new study found. Researchers investigated the risk of incident major depressive disorder (MDD) attributable to a range of sleep disorders. They found:
- 65,739 individuals who had first onset of depression between 1995‒2013 were selected as cases.
- For each case, a set of 20 controls of the same sex, birth month, and year who had not had depression by the date that the case was diagnosed were selected at random (n=1,307,580).
- An increased risk of incident depression in cases was found for all sleep disorders analyzed.
- Those diagnosed with a sleep disorder in the last 6 months were at highest risk of developing depression vs those with at ≥1 year since diagnosis.
Byrne EM, et al. Sleep disorders and risk of incident depression: A population case-control study. [Published online ahead of print June 17, 2019]. Twin Res Hum Genet. doi: 10.1017/thg.2019.22.
In this article, Byrne et al. find that having any sleep disorder within 6 months was highly associated with developing a major depressive episode. This makes some intuitive sense because insomnia, for example, is a key defined symptom of DSM-5 Major Depressive Disorder. In these cases, insomnia may have been the sentinel or first symptom of a developing depressive episode. Alternatively, some consider both unipolar, and more so bipolar disorder also a circadian disorder of sorts, in that insomnia often predates a spell of mania. In this research, insomnia or other disorders predated unipolar symptom development. Theoretically, if clinicians were able to aggressively treat insomnia or circadian rhythm sleep disorders, then might we actually prevent full depressive episodes from developing in mood disorder patients? —Thomas L. Schwartz, MD; Senior Associate Dean of Education, Interim Chair/Professor of Psychiatry, SUNY Upstate Medical University.