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Chronotype may predict depression in midlife, older women
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Chronotype may be a predictor of depression among middle- to older-aged women, researchers found.
Sensitivity analyses revealed that women with early chronotypes who naturally went to bed early and woke early were at slightly lower risk for depression.
“While the implications of the circadian system and circadian photoreception pathways with mood seem established, it is unclear to what extent inter-individual differences in chronotype per se are linked to depression,” Céline Vetter, PhD, director of the Circadian and Sleep Epidemiology Laboratory at University of Colorado, and colleagues wrote in the Journal of Psychiatric Research. “Prospective analyses are crucial to better understand the directionality of the association of chronotype with depression, and the present study addresses this gap.”
The investigators assessed the connection between chronotype and depression among 32,470 midlife and older women enrolled in the Nurses’ Health Study II. Participants who were without depression at baseline in 2009 self-reported their chronotype as early, intermediate or late, then provided updated information on their depression status using biennial questionnaires in 2011 and 2013. Researchers analyzed incident depression across chronotype categories.
Over the 4-year follow-up period, there were 2,581 cases of incident depression. Vetter and colleagues found that women who reported early chronotypes had a modestly lower risk for depression compared with intermediate chronotypes after multivariable adjustment (HR=0.88; 95% CI, 0.81-0.96) and those who reported late chronotypes had a similar risk (HR = 1.06; 95% CI, 0.93-1.2).
Similar results were observed when the authors restricted analyses to women who reported normal sleep durations of 7 to 8hours each day and had no history of nightshift work at baseline.
“Overall, our findings suggest that chronotype is a predictor of depression among midlife and older women, independent of environmental and lifestyle factors,” Vetter and colleagues wrote. “Future studies are warranted, especially to further elucidate the interrelationship between circadian phenotypes, genetics, and mood disorders.” – by Savannah Demko
Disclosure: The authors report no relevant financial disclosures.