A study by researchers at University of Colorado Boulder and the Broad Institute of MIT and Harvard has provided some of the strongest evidence yet that chronotype – a person’s propensity to sleep at a certain time – influences depression risk.
“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?” said senior author Celine 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.”
The researchers used statistical data from 840,000 people and found that each one-hour sleep midpoint (halfway between bedtime and wake time) corresponded with a 23 per cent lower risk of major depressive disorder.
The data suggested 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%; if they go to bed at 11pm, they could cut it by about 40%.
Why? Some research suggests that getting greater light exposure during the day, which early-risers tend to get, results in a cascade of hormonal impacts that can influence mood.
“We live in a society that is designed for morning people, and evening people often feel as if they are in a constant state of misalignment with that societal clock,” said lead author Iyas Daghlas.
I regard morning larks in a new light.
