If you've ever doubted whether to stay up or go to bed, a new study will definitely convince you that going to bed earlier and waking up earlier has a major impact on our mental health: Early-to-bed types have a significantly lower risk of suffering major depression, according to an important new study published the journal JAMA Psychiatry. 

The new research underscores what most of us already know: Sleep is integral to our physical and mental health; It's the time when our body and brain recover from the day's events, processes our emotions, and prepares us for the day ahead. The effects of a poor night's sleep are obvious in our performance, resilience, and focus, but the latest findings now show that lack of sleep, even in small increments, can hurt us over time by increasing our risk of depression, heart disease, and diabetes.

Researchers at the University of Colorado Boulder and the Broad Institute of MIT and Harvard have published one of the first large-population studies to evaluate exactly how much loss of sleep can impact our long-term mental health, and what we need to do about it.

Research Suggests a Link Between Staying Up Late and Depression

Previous studies have found that night owls have twice the odds of having depression as those who hit the hay early, regardless of the total amount of sleep they clock. The problem with these studies is that having a mood disorder can disrupt sleep in the first place, so it was unclear whether depressives stay up late or staying up late contributes to depression. In addition, most of these prior studies didn’t account for other environmental factors that can impact sleep and mood, which leaves researchers questioning the validity of these results.

A 2018 study, published by the same author as the new study, found that 32,000 nurses who were “early risers” were 27 percent less likely to develop depression over four years than their late-to-bed counterparts. When environmental factors were accounted for, the results found that chronotype (behavior that influences your body to want to sleep at a certain time) also influenced depression risk.

So in the new study, the researchers wanted to determine if shifting your sleep time to go to bed earlier could be protective against depression, and if so, how much time you should shift.

New research recommends going to sleep 1 hour earlier

The new study published in the journal, JAMA Psychiatry, studied sleep and mental health patterns of 840,000 people and showed that a person's natural tendency to go to sleep at a certain time (due to their genetics and behaviors) influences their 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?” comments senior author and assistant professor of integrative physiology at CU Boulder, Celine Vetter. “We found that even one-hour earlier sleep timing is associated with significantly lower risk of depression.”

A big reason behind the results boils down to our genetics. We have over 340 different gene variations and 12 percent to 42 percent of our sleep timing preference comes from genetics. That’s why researchers from this study factored in the genetic data by either having them fill out a preference questionnaire or having them wear sleep trackers.

The results found about one-third of the subjects identified as morning people, nine percent were night owls, and the remainder were somewhere in the middle. The average sleep midpoint (halfway between bedtime and wake time) was 3 a.m. which means they fell asleep at 11 pm and woke up at 6 am.

Researchers took this information and combined it with genetic information, medical and prescription records, and surveys regarding the diagnosis of major depressive disorders to uncover that those with the genetic variants which cause them to be early risers have a lower risk of being depressed.

With each one hour earlier midpoint time--meaning going to bed an hour earlier and waking up an hour earlier--the subjects had a 23 percent lower risk of major depressive disorder. For example, if someone who normally goes to bed at 1 a.m. started to go to sleep at 12 a.m. and sleeps the same length of time, their risk of depression goes down by 23 percent. Going to bed another hour earlier (11 p.m.) could cut their depression risk by 40 percent.

Unfortunately for those that are already early risers, the results do not indicate whether they can benefit from going to bed and getting up even earlier.

Sleep and Depression

Although there could be several factors that lead to these results, research has indicated that the increase in light exposure early risers get throughout the day can impact hormones that influence mood. When we are exposed to sunlight, our brain releases serotonin, known as the “happy chemical” due to its ability to boost our mood and make us feel calm and focused.

“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,” Iyas Daghlas, M.D., and the lead author of the study said in an interview.

Although Daghlas states that this study provides solid evidence that the effect of sleep timing can impact depression, he still stresses that further randomized clinical trials need to be completed in order to definitively confirm that correlation.

If you’re looking to begin to transition to an earlier bedtime, Vetter offers some advice. “Keep your days bright and your nights dark,” she recommends. “Have your morning coffee on the porch. Walk or ride your bike to work if you can, and dim those electronics in the evening.”

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