If an ounce of prevention is worth a pound of cure, here's a strategy that may help boost your mental health: Spend the next week observing your daily habits. You can jot them down in a journal to keep track.

How well are you sleeping? Are you eating foods that nourish you? Did you make time for a favorite hobby and exercise? Did you gather with friends or loved ones?

Your answers to these questions may help explain your mood — and your risk of depression too. In fact, a new study finds that people who maintain a broad range of healthy habits, from good sleep to physical activity to strong social connections, are significantly less likely to experience episodes of depression. Researchers used Mendelian randomization — using genetics to study behavior — to confirm a causal link between lifestyle and depression. They found a reduction in the risk of depression held up even among people who have genetic variants that make them more susceptible.

"I think the biggest surprise is that if you have a favorable lifestyle, you can reduce the risk of your getting depression by 57%, which is really quite a massive amount," says study author Barbara Sahakian, a clinical psychologist and neuroscientist at the University of Cambridge.

The study included data from nearly 300,000 people in the UK Biobank database initiative. Researchers identified seven healthy habits and found that people who maintained most of them — five or more— cut their risk of depression by 57%. Researchers also analyzed markers of inflammation, including C-reactive protein, which is linked to depression, and found that a healthy lifestyle is linked to better scores. C-reactive protein concentrations rise in response to inflammation.

Of course, serious depression needs to be treated, and medications and therapy help many people feel better. But in recent years, as science has evolved, it has become clear that depression is not just a chemical imbalance. It's much more complex, and increasingly, a body of evidence points to the importance of habits and behaviors to help keep mental health strong.

1. The power of rest

At the top of the list is a good night's rest. Sleeping seven to nine hours per night, on average, reduced the risk of depression by about 22% in the study. "A lot of us think of sleep as a kind of a passive process, but it's an incredibly active process," Sahakian says.

Not only does sleep enable us to consolidate memories, helping us remember what we've learned during the day, but research shows it plays a key role in keeping our immune systems strong. For instance, a well-rested person is better at fending off the common cold. And though dreaming is still a bit of a mystery, the idea that dreams may help us regulate our emotions goes back decades.

If you have insomnia or trouble sleeping, there's lots of evidence that these strategies, based on cognitive behavioral therapy, can help.

2. Exercise is an elixir

There's a solid body of evidence linking physical activity to improved moods. A previous study, based on data from Centers for Disease Control and Prevention surveys, found that people who exercise regularly report fewer days of bad mental health.

And a recent meta-analysis found that physical activity was more effective than medications in reducing symptoms of depression. Antidepressant medicines tend to be faster in treating an episode of depression, says Douglas Noordsy, a psychiatrist with the Stanford Lifestyle Medicine Program. "But physical exercise has more durable effects than an antidepressant does," he says.

For some people, medication gives them a benefit in the beginning, but then it fades over time, Noordsy says. "Whereas a lifestyle change can have a more permanent and lasting effect." Noordsy and his colleagues use a range of evidence-based recommendations and tools, from medicines to therapy to behavioral approaches including fitness, nutrition, sleep and stress management, to help empower patients.

3. Good nourishment is a necessity

The researchers found that people who maintained a healthy pattern of eating were less likely to have an episode of depression. "I always recommend the Mediterranean diet or the MIND diet," says Sahakian. Multiple studies show that a plant-forward approach — full of greens, vegetables, berries, whole grains, lean proteins including beans and healthy fats including nuts — can help reduce the risk of disease.

The MIND diet is a mashup of a Mediterranean diet and the DASH diet, which has been shown to reduce hypertension, diabetes, heart attack and stroke. One study found that eating a salad each day is tied to sharper memory and slower cognitive decline among healthy seniors.

And a randomized controlled trial found that college students who followed a Mediterranean diet improved their depression scores after three weeks, whereas depression scores among students who continued to eat lots of refined carbohydrates, ultraprocessed foods and sugary snacks and drinks remained higher.

4 & 5. Limit alcohol and don't smoke

Having a glass of wine or a beer helps many people feel relaxed, but limiting alcohol consumption to one drink a day or less for women and two drinks a day or less for men is the recommendation in the Dietary Guidelines for Americans. People who regularly consume more than this amount have an increased risk of certain cancers and a higher risk of depression. Why?

People think of alcohol as a pick-me-up, but actually alcohol is a central nervous system depressant that slows down brain activity. The more you drink, the more you chase the temporary high, which can increase the risk of dependence.

There are lots of strategies to help people drink less, and increasingly, as the sober-curious movement grows, there are people taking a break from drinking.

And when it comes to smoking, there's loads of evidence that tobacco is not a healthy habit. And there are programs to help people quit, including medications, therapy and smoke-free apps.

6. Limit sedentary time by cutting back on screen time

At a time when cultural norms and the pull of technology are leading to more time in front of screens, there's growing evidence that this can harm our physical and mental health. "Sedentary behavior is very bad," Sahakian says.

Humans are meant to move, and though binge-watching your favorite streaming shows may be fun in the moment, if this behavior sets in as a daily habit, you're probably spending too much time on the sofa and not enough time interacting with people or moving.

"The rate of mental health problems is increasing in close correlation with the deterioration in lifestyle factors," Noordsy says. As helpful as smartphones and internet-based technologies are in making our lives convenient, it's common for people to sit for hours and hours playing video games or scrolling.

"We know that long periods of being sedentary are an independent risk factor for depression, independent from how much exercise you get," Noordsy says. So even if you go out for a 30-minute jog or bike ride every day, if you then spend most of the day in front of a screen, it can have a deleterious effect on your mental health.

This is a particular concern for young people who spend a lot of time on social media. At a time when teenagers are facing high rates of depression, anxiety and loneliness, there is mounting evidence that social media can exacerbate and even cause these problems.

Here are some effective strategies to help people cut back on screen time, including scheduling a one-day break each week and turning off notifications, bells and chimes, so we feel less tethered to our devices.

7. Cultivate friendships and social connections through hobbies

This may sound obvious, but spending time with people we like, especially when we're engaged in activities we like, helps boost our mood. Another new study, published in Nature Medicine, based on surveys of people in 16 countries, finds that people 65 and older who have hobbies report higher life satisfaction and less depression.

Noordsy says people tend to know about the connections between crossword puzzles and the slowing of cognitive decline, but there's not as much awareness that hobbies, whether it's gardening, knitting, painting, playing games or volunteering, can help boost our moods. As the authors of the study point out, hobbies involve imagination, novelty, creativity, relaxation and stimulation.

"It's really nice to have a specific effect on mental health," Noordsy says of the new study. "Hobbies really involve aspects of creativity and engagement," compared with the passive pursuits of watching TV or scrolling social media, he says. Whether it's knitting or playing bridge — hobbies that may be familiar to our grandparents — "they keep us connected in ways that people have been connected over generations," Noordsy says.

The takeaway

Just as we can take steps to reduce our risk of chronic diseases, the research shows we can also take steps to reduce the risk of depression, Sahakian says. And oftentimes, the same strategies that promote physical health are also good for our mental health.

It's probably not possible to eliminate depression, which afflicts millions of Americans. Many people do improve with medicines and therapy, and now there's a growing body of evidence to show lifestyle medicine can help people alter their behaviors. "I certainly see some people who can effectively manage their symptoms with lifestyle interventions," Noordsy says. The key is for people to get the support they need to navigate change.