As a psychiatrist and neuroscience researcher, I've spent 27 years studying the surprising connections between our mental health, physical health and brain health.

I've also learned a lot from my personal journey. In my 20s, I was diagnosed with metabolic syndrome, a combination of disorders that increases the risk of cardiovascular disease and diabetes.

But by making some lifestyle changes, I was able to overcome it in just a few months. To continue staying sharp, energized and healthy, here are six things I never do:

1. I never load up on high-carb foods.

Diet plays a role in obesity, diabetes and heart health, but most people don't realize that it also has profound effects on the brain.

I reversed my metabolic syndrome by committing to a low-carb diet. Generally, low-carb diets eliminate or cut back on grains, baked goods, sweets and fruits that are high in sugar or starch.

I typically have eggs for breakfast. Throughout the day, I eat vegetables, fruits, and a good amount of meat, fish and poultry. This has helped me maintain a healthy weight and keep my blood sugar low.

2. I never take more than 2 days off from exercising.

A study of 1.2 million Americans found that exercise is good for mental health.

For me, the optimal workout is 45 minutes, three to five times a week. In addition to stretching and core exercises, I lift weights, run, cycle, swim and take brisk walks.

I don't push myself to exercise every day, but I also never take more than two days off from aerobic activities.

3. I never get less than 7 hours of sleep a night.

Poor sleep can result in cognitive impairment that might lead to a greater risk of Alzheimer's disease over time. It can also impact mood and contribute to depression.

When you sleep, your body enters a "rest and repair" state. The brain undergoes many changes in neurons that play a role in learning and memory consolidation. Without sleep, cells can fall into a state of disrepair and begin to malfunction.

The amount of sleep people need varies, but I always get in at least seven hours a night. I'm usually in bed by 8 p.m. or 9 p.m., and wake up at 4 a.m. The "early to bed, early to rise" routine makes me sharper and more focused throughout the day.

4. I never drink alcohol.

I used to drink regularly, and would sometimes have a glass of wine in the evenings to relax.

But in June 2020, I decided to give it up for one month. Within weeks, I noticed improvements in my sleep and productivity, so I decided to quit drinking altogether. What's shocking is that I don't miss it at all.

This doesn't mean you should give up drinking completely, but the benefits that we once thought alcohol conferred are now being questioned. In a study of over 36,000 people, consuming even one to two drinks a day was associated with brain atrophy or shrinkage.

5. I'm never done with self-growth.

Exploring your emotional health through psychotherapy can be life-changing. It can help you understand who you are and what you want from life, which will strengthen your sense of purpose.

Psychotherapy that focuses on empathy, relationships, social skills or improving cognitive abilities can strengthen brain circuits that have been underdeveloped.

6. I never lose sight of my purpose in life.

Humans are driven to have a sense of purpose. I believe this is hardwired into our brains. When people lack a sense of purpose, it can induce a chronic stress response and lead to poor cognitive function.  

Remember that purpose is multifaceted. It involves relationships with other people, yourself and your community. We should all aim to have least one role in society that allows us to contribute and feel valued.

This can be as simple as having household chores, or take the form of being a student, employee, caretaker, volunteer or mentor.

Christopher Palmer, MD is a professor of psychiatry at Harvard Medical School and the author of "Brain Energy: A Revolutionary Breakthrough in Understanding Mental Health." For the past 27 years, he has been an academic physician with administrative, research, educational, and clinical roles. Follow him on Twitter @ChrisPalmerMD.

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