Here's Why You Feel Healthier, Happier & More Energetic In The Summer

As a functional medicine practitioner who primarily consults via webcam, I see this summer-loving phenomenon no matter where my patients live. So what is it about the warmer months? This is the science of summer.

Shorter grey fall and winter days can lead SAD or seasonal affective disorder. In fact, about 6 percent of people have winter depression and up to 20 percent more have mild SAD. Four times more common in women, SAD is alleviated in the longer, sunnier days of summer. One mechanism for this is the brain's ability to produce more of your feel-good neurotransmitter serotonin with sunlight.

Another factor to consider is fresh produce. There's something ancestral about eating fresh, seasonal fruits and vegetables from local farms during the summer months. These foods are rich in vitamins and phytonutrients that boost your immune system, brain, and mood. If you feel better in the summer months, it may be as simple as an increase in foods from the farmers market.

Good ol' vitamin D, the sunshine vitamin, is synthesized when you're outside in the sun. Vitamin D is super important—responsible for hundreds of different pathways that control your mood, immune system, and brain. Every single cell of your body needs vitamin D to function optimally, and summer it the ideal for time in the sun.

There's no denying that spending time in nature is healing to the mind and body. During the colder months, we tend to spend more of our days inside and disconnected with nature. One study, published in the Proceedings of the National Academy of Sciences shows just how remarkable nature is. The group of people who walked for 90 minutes in nature reported fewer negative thoughts compared to the group who walked in the city. Functional MRI brain scans also revealed less activity in the subgenual prefrontal cortex, an area of your brain that plays a role in mood disorders and negative thoughts in the nature group. Those who walked in the city showed none of these benefits. Sorry city folks.

Since we are inside more during the chilly time of the year, this can be a breeding ground for viruses. In rooms with poorer ventilation, colds were more likely to thrive and the cold virus also tends to spread more1 during colder months. Other studies from the NIH found that the flu virus actually became tougher during winter.

When sunlight hits your eyes, a message is sent to your brain's pineal gland to slow down producing your sleepy-time hormone melatonin. As the sun goes down it signals your body to ramp up melatonin for you to get a good nights rest. During darker, winter days the sunlight can't shut off the melatonin mechanism as much during the day, leading to lower production at night, causing poorer sleep.

One fascinating study published in the scientific journal Nature, found that around 25 percent our DNA actually changes with the seasons! The study found that during the winter months, DNA changes were (presumably) occurring to prepare for the increase in viruses that spread more during the winter. In the summer, different sets of genes are more greatly expressed, specifically genes that govern blood sugar balance, which calms cravings and will help burn winter fat.

So does the weather play in a role in your mood, energy and health? Absolutely. But it's actually not nearly as important as what you eat, your social ties, your outlook on life, and your activity levels.