Shifting your sleep and wake-up time earlier by just an hour may lower your risk of major depression by as much as 23 percent, according to a recent genetic meta-analysis published in JAMA Psychiatry.
We’ve long understood that the amount of sleep we get affects our health. But most don’t realize that sleep timing — when we go to bed and wake up — also plays a key role.
The study, conducted by a team of researchers from the University of Colorado Boulder, and the Broad Institute of MIT and Harvard, found strong evidence that sleep chronotype — a person’s propensity to sleep at a certain time — influences depression risk.
The researchers note that 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. But because mood disorders themselves can disrupt sleep patterns, researchers have had a hard time deciphering effects.
“We have known for some time that 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?” says senior author Céline Vetter, PhD, a University of Colorado assistant professor of integrative physiology. “We found that one-hour-earlier sleep timing is associated with significantly lower risk of depression.”
What causes the benefits? Lead author Iyas Daghlas, MD, a research fellow at Harvard Medical School, theorizes that society is designed for morning people, leaving evening types in a state of misalignment between their biological clock and the societal clock.
And daylight itself may play a role, he says: “It’s possible that light has a protective effect on your risk of being depressed. People who are early-morning types tend to be out and about and are exposed to more light than evening types who will wake up later and stay up later.”
While your sleep chronotype is in part genetic, it is also influenced by environment, reports Vetter. She offers the following advice for shifting your sleep timing.
- Get plenty of daylight exposure and keep your bedroom dark at night. “Light is a powerful environmental agent for the biology underlying interindividual differences in how early or late we [go to bed], and morning light is one of the most powerful tools to shift individuals to an earlier sleep schedule.”
- Change some habits. Exercise in the morning; avoid drinking caffeine or eating hearty meals too close to bedtime; avoid eating too much sugar; and avoid using screens at least one hour prior to sleep.