A new genetic study published in the journal JAMA Psychiatry , carried out in 840,000 people, suggests that advancing the time we wake up a little earlier each day would already be enough to reduce the probability of suffering major depression.
Specifically, according to this study by researchers from the University of Colorado Boulder and the Broad Institute of MIT and Harvard, waking up an hour earlier each day will already be enough to reduce the probability of depression by 23%.
The influence of the chronotype
Previous observational studies have shown that night owls are 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 figuring out what causes what .
To get a clearer idea of whether changing sleep time earlier is really protective and how much change is required, the study’s lead author, Iyas Daghlas , turned to data from the DNA testing company 23 and Me and the UK Biobank biomedical database. Daghlas thus used a method called "Mendelian randomization" that takes advantage of genetic associations to help decipher cause and effect .
The study presented thus reveals some of the strongest evidence to date that chronotype (a person’s propensity to sleep at a given time) influences the risk of depression. It is also one of the first studies to quantify how much or little change is required to influence mental health .
Specifically, each midpoint of sleep an hour earlier (midway between bedtime and waking time) corresponded to a 23% lower risk of major depressive disorder. In other words, if someone who normally goes to bed at 1 am goes to bed at midnight and sleeps the same amount of time, they could reduce their risk by 23%; if they go to bed at 11pm, they could reduce it by about 40%. Still, it remains unclear whether those who are already early risers could benefit from waking up even earlier .
The reason for this is not known. Perhaps, getting more exposure to light during the day, as early risers tend to have, results in a series of hormones that can influence mood , but it certainly gives force to the saying "who gets up early, God helps ". Even if it is only emotionally speaking.