A new study shows how getting up early can reduce a person’s risk of major depression by 23%. A groundbreaking genetic analysis reveals that waking up just an hour earlier can produce these results.
The newspaper JAMA Psychiatry published the article on May 26, 2021
Researchers from the University of Colorado Boulder and the MIT-Harvard Board Institute led the study. It included 840,000 people, one of the largest studies of its kind to date. Research provides strong evidence that chronotype, the tendency of a person to sleep at a specific time, affects the risk of depression.
It is also one of the first studies to determine the change in sleep habits necessary to influence mental health. Many people have experienced drastic changes in their lives and sleep patterns during the pandemic. As more people have moved to work and attend school from home, many have delayed bedtime. Perhaps this new study helps shed light on the importance of lying down and up early.
“We have known for some time that there is a relationship between sleep timing and mood, but a question we often hear from doctors is: how soon do we need to change people to see a benefit?” said lead author Celine Vetter, assistant professor of integrative physiology at CU Boulder.
“We found that even an hour before bedtime is associated with a significantly lower risk of depression.”
Previous observational studies demonstrated how night owls they are twice as likely to develop depression as those who wake up early. This is maintained no matter how many hours they sleep. However, many people with mood disorders have a hard time falling asleep or staying asleep. This makes it more difficult for researchers to determine whether mental illness causes insomnia or vice versa.
The new study may have found the answer.
- some of the sample sizes were too small
- others were based on questionnaires that covered only a time point
- did not consider environmental factors that can affect both sleep time and mood
However, there was one large long-term study that included 32,000 nurses in 2018. The study, conducted by Vetter, found that up early led to a 27% reduction in the risk of depression over a four-year period. However, the findings left out a crucial question: How early do people need to wake up to reduce depression?
So in this study, the researchers wanted to quantify exactly what it means to be an early riser. They had two main goals: to determine whether getting up early really protects mental health and what waking time provides the most benefits.
To do this, lead author Iyas Daghlas, MD, analyzed data from DNA testing company 23andMe and the UK Biobank biomedical database. Next, Daghlas used a method called “Mendelian randomization.” This technique investigates causal relationships between modifiable risk factors and health outcomes using genetic variations.
Daghlas, a recent graduate of Harvard Medical School, says this:
“Our genetics are established at birth, so some of the biases that affect other types of epidemiological research tend not to affect genetic studies.”
The research found that more than 340 common genetic variants affect a person’s chronotype. One of them includes variants in the PER2 gene, known as the “clock gene.” Experts estimate that genetics play a role between 12 and 42% of our sleep tendencies.
The researchers then analyzed de-identified genetic data (removing data that could identify patients) on variants from 840,000 people. This included data from 85,000 people who had used portable sleep trackers for seven days. It also included 250,000 people who had answered questionnaires on sleep preferences. This gave the researchers a more detailed picture, so far, of how genetic variants impact our circadian rhythm.
The study found that getting up early greatly reduces the risk of depression
The largest of the samples revealed the following:
- about a third of participants identified as early risers
- 9% reported being night owls
- the rest fell somewhere in the middle
- the average sleep midpoint was 3am, which means they went to bed at 11pm and woke up at 6am
After collecting this information, the team analyzed the data from another sample. It included genetic information, anonymous prescription and medical records, and major depression diagnosis surveys.
Finally, the team used novel statistical techniques to ask the million dollar question. Those who are in the habit of waking up early due to a genetic predisposition also have a lower risk of depression?
The answer? A definite yes.
The study found that with each midpoint of sleep an hour earlier, the risk of significant depression was reduced by 23%. Midpoint refers to the midpoint between bedtime and wake-up time.
So let’s say someone normally falls asleep at 1 in the morning. If they went to bed at midnight and slept the same, they would have a 23% lower risk of depression. If they fell asleep even earlier, at 11 p.m., their risk would drop by about 40%.
Researchers are not sure if these benefits would apply to those already in the habit of up early. However, for night owls or people somewhere in between, going to bed and getting up earlier would help.
Final thoughts on how getting up early benefits mental health
Previous research suggests that getting up early reduces depression due to increased exposure to light. People who wake up in the sun receive hormonal benefits that can improve mood. However, experts believe that social norms also come into play. Having a very different circadian rhythm than other people can feel isolate and depressing.
“We live in a society that is designed for people in the morning, and people in the evening often feel like they’re in a constant state of misalignment with that social clock,” Daghlas said.
He also said that to confirm whether getting up early can reduce depression, a large randomized clinical trial is needed. “But this study definitely shifts the weight of evidence toward supporting a causal effect of sleep time on depression.”
If you want to get into the habit of getting up early, follow this advice from Vetter:
“Keep your days bright and your nights dark,” she says. Have your morning coffee on the porch. Walk or bike to work if you can, and dim those electronic devices at night. “