A healthy lifestyle — especially getting enough sleep — may offer substantial protection against depression, new research suggests.
The study, of more than 287,000 British adults, found that several lifestyle factors seemed to curb the risk of developing depression over the next nine years. Among them were eating a healthy diet, getting regular exercise, staying socially active, not smoking and — most importantly — regularly having a good night's sleep.
Each healthy habit mattered on its own, the study found. People who exercised had a lower risk of future depression than couch potatoes did, for example.
But the more good habits, the better: Study participants who adhered to at least five of seven healthy habits had a 57% lower risk of depression, versus those who followed none or only one.
Major depression is a complex disease, with genetic vulnerability playing a key role.
And one of the important findings in this study, the researchers said, was that a healthy lifestyle benefitted people, regardless of the genetic cards they've been dealt.
"Lifestyle has a strong protective role across different levels of genetic risk for depression," said study author Christelle Langley, a research associate at the University of Cambridge.
The findings, published Sept. 11 in the journal Nature Mental Health, are based on data from the UK Biobank. It's a huge research project collecting health and genetic information from about a half-million middle-aged and older British adults.
In the study, Langley and her colleagues focused on over 287,000 participants who were depression-free when they entered the study between 2006 and 2010. All reported on their lifestyle habits at that time.
Over the next nine years, just under 13,000 people were newly diagnosed with depression. The risk was lower, however, among those who'd reported healthier lifestyles at the outset.
The big seven factors were:
- Sufficient sleep (7 to 9 hours a night)
- Regular exercise -- including moderate activities, like brisk walking, on most days of the week
- Limiting screen time and other sedentary activities
- A healthy diet high in foods like fruits and vegetables, fish and whole grains
- Not smoking
- Regularly seeing family and friends
- Drinking no more than moderate amounts (at most one drink per day for women, and two per day for men)
Sleep was the single most protective factor, the researchers found. People who got enough shut-eye were 22% less likely to develop depression than those with poor sleep habits. Not smoking was nearly as protective.
But, Langley said, people saw the most benefit when multiple good habits were practiced together.
Among those who reported at least five of the seven healthy habits, the risk of depression was 57% lower, versus people who adhered to no more than one. In the intermediate group — two to four healthy habits — depression risk was cut by 41%.
Next, the researchers looked at genetic risk. They analyzed participants' blood samples, looking for genetic variants that have been linked to depression, and assigned each person a genetic risk score.
Again, healthy habits appeared powerful -- guarding people against depression regardless of their genetic risk, Langley said.
The findings do not prove cause-and-effect, but they are "compelling," said Dr. Ken Duckworth, chief medical officer at the nonprofit National Alliance on Mental Illness.
He noted that the genetics of depression are complex and have not been "nailed down," so the risk scores assigned in this study have limitations.
But the bottom-line message is a positive one, Duckworth said: "You're not helpless vis-a-vis your genes."
Exactly why healthy habits can be a buffer against depression is unclear. But the researchers looked for clues in study participants' MRI brain scans and blood samples.
They found that healthy lifestyle habits correlated with a larger tissue volume in certain brain structures, including the hippocampus, amygdala and thalamus.
Langley said the larger tissue volumes hint at better "cognitive control and emotional regulation," which might help explain the connection between a healthy lifestyle and lower depression risk.
Although the findings point to the power of having many healthy habits, Duckworth said that people can focus on the "small wins" each day.
"Going for a walk in the park is doable for most people, even if they feel like they don't have the energy or the motivation," he said.
Plus, small steps can lead to other changes: If you're more active, you might sleep better. A daily walk gets you out in the world, and possibly talking to more people.
"These things all build on each other," Duckworth said.