EARLY BIRDS ARE HAPPIER BIRDS
Retiring for the night and getting up an hour earlier has been strongly linked to lower rates of depression.
Going to bed and waking up just one hour earlier cuts depression risk by 23 per cent, a study from the University of Colorado and the Broad Institute of MIT and Harvard has found. The study of 840,000 people found that shifting sleep time earlier reduces the risk of depression because getting greater light exposure during the day results in a cascade of hormonal impacts that can influence mood. “We have known for some time there is a relationship between sleep timing and mood, but a question we often hear from clinicians is: How much earlier do we need to shift people to see a benefit?” said senior author Céline Vetter, assistant professor of integrative physiology at CU Boulder. “We found that even one-hour earlier sleep timing is associated with significantly lower risk of depression.”
Previous observational studies have shown that night owls are as much as twice as likely to suffer from depression as early risers, regardless of how long they sleep. The researchers assessed genetic data on up to 850,000 individuals, including data from 85,000 who had worn wearable sleep trackers for seven days, and 250,000 who had filled out sleep-preference questionnaires. In the largest of these samples, about a third of surveyed subjects self-identified as early birds, 9 per cent were night owls and the rest were in the middle.
The researchers found that each one-hour earlier sleep midpoint (halfway between bedtime and wake time) corresponded with a 23 per cent lower risk of major depressive disorder. This suggests that if someone who normally goes to bed at 1am goes to bed at midnight instead and sleeps the same duration, they could cut their risk by 23 per cent; if they go to bed at 11pm, they could cut it by about 40 per cent. For those wanting to shift themselves to an earlier sleep schedule, Vetter says: “Keep your days bright and your nights dark. Have your morning coffee on the porch. Walk or ride your bike to work if you can, and dim those electronics in the evening.”