find benefits of waking up an hour earlier

To wake up just an hour before could reduce a person’s risk of major depression by 23%, according to a large genetic study.

The study, which collected data from 840 thousand people, was carried out by researchers at the University of Colorado Boulder and the Broad Institute (MIT and Harvard University), USA, produced some of the strongest evidence to date that the chronotype (a person’s propensity to sleep at any given time) influences the risk of depression.

Published in JAMA Psychiatry magazine, it is also one of the first books to quantify what modification is needed to influence mental health.

The pandemic extended hours of sleep many adults, children and adolescents who have seen their routines altered by turning to telecommuting and virtual lessons. According to the researchers, the findings are of particular importance as more and more people return to the presence in jobs and schools.

Sleep and mood

“We have known for some time that there is a relationship between sleep time and mood, but a question we regularly hear from doctors is this: How much does it take to change to see a benefit? “commented lead author Celine Vetter, assistant professor of integrative physiology at the University of Colorado.

“We have found that even quitting an hour earlier is associated with a significantly lower risk of depression,” he replied.

Previous observational studies had shown that night owls have the twice as likely to suffer from depression as early risers, however long they sleep. But because mood disorders themselves can disrupt sleep patterns, researchers struggled to decipher what was causing what.

In other studies, the small sample size was a limitation. They were based on questionnaires that, among other things, did not take into account environmental factors that could influence both sleep time and mood, which can lead to confusion in the results.

What does it mean to be an early bird?

In 2018, Vetter published a large, long-term study of 32,000 nurses, showing that ‘early risers’ were up to 27% less likely to develop depression over the course of four years, but it raised the question. : what does it mean to be an early riser?

To get a clearer idea of ​​whether waking up earlier is truly protective and what change is needed, lead author Iyas Daghlas turned to data from DNA testing company 23 and Me and the Biomedical Database. Kingdom Biobank. United. Then he used a method called “Mendelian randomization,” which takes advantage of genetic associations to help decipher cause and effect.

“Our genetics are established at birth, so some of the biases that affect other types of epidemiological research tend not to affect genetic studies,” said Daghlas of Harvard Medical School.

Over 340 common genetic variants, including variants of the so-called “clock gene” PER2, influences a person’s chronotype, and genetics collectively explain between 12% and 42% of our preference for sleep time.

Written in the genes

The researchers evaluated unidentified genetic data from these variants of up to 850,000 people, including data from 85,000 who had used sleep trackers for 7 days and 250,000 who completed questionnaires on sleep preferences. This has provided them with a more detailed picture, so far, of how variant genes influence how we sleep and wake up.

In the largest of these samples, about a third of the respondents identified themselves as morning larks, 9% were owls (night owls) and the rest were in the middle. Typically, the midpoint of sleep was at 3 a.m., meaning they went to bed by 11 p.m. and woke up at 6 a.m.

With that information in hand, the researchers drew on a different sample that included genetic information as well as anonymous medical and prescription records and investigations into major depressive disorder diagnoses.

Using new statistical techniques, they asked: who has genetic variants that predispose them to being early risers also have a lower risk of depression?

The answer they came up with was a categorical yes.

Each midpoint of sleep an hour earlier (midway between bedtime and waking time) was a 23% reduced risk of major depressive disorder.

This suggests that if a person who normally goes to bed at 1 a.m. goes to bed at midnight and sleeps the same time, they could reduce their risk by 23%; if you go to bed at 11pm, you could reduce it by about 40%.

It’s not clear from the study whether those who are already early risers could benefit from waking up even earlier. But for those who are in the mid-range or in the evening, going to bed and getting up earlier would probably help.

What could explain this effect?

Some research suggests that obtaining a increased exposure to light during the day, which early risers often have, leads to a cascade of hormonal impacts that can influence mood.

Others point out that having a body clock, or circadian rhythm, which has different tendencies than most people, can in itself be a factor associated with depression.

“We live in a society that designed for morning people, and evening people often feel like they are in a constant state of misalignment with this social clock“considers Daghlas.

The researcher points out that a large randomized clinical trial is needed to definitively determine that an early bedtime can reduce depression. “But this study definitely shifts the weight of evidence to support a causal effect of the dream hour about depression, “asserted.

For those who want to go to bed and get up earlier, Vetter advises: “Keep your days bright and your nights dark. Have coffee in the morning, outside. If you can, walk or cycle to work and cut down on your electronics at night. “