A lack of sunshine in your life could be more damaging than you think.

By Zee Krstic
June 18, 2019
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Flamingo Images via Getty

Spending time outdoors in the sunshine feels great, and previous research has suggested that there are specific health benefits associated with being outside, especially as it relates to cardiovascular health. But if you've ever felt compelled to throw open your shades first thing in the morning, or have been jockeying for the sunbathed desk by the window at work, you know that even indirect exposure to sunlight can drastically affect your psyche. That's because sunlight directly impacts our mental and physical health, and can have far-reaching influences beyond the common "winter blues." "It's a really broad area of research," says Arie Greenleaf, Ph.D., a professor of counseling at Seattle University, "but researchers are beginning to understand the scope of sunlight's effect on essential functions."

For most, a lack of sunlight can lead to what's commonly known as seasonal depression, referred to clinically as Seasonal Affective Disorder or SAD. The condition is a form of depression that can lead to sedentary behavior and cause people to spend more time inside (and away from natural light). Limited outdoor time isn't just a winter-season problem: Modern work schedules keep people indoors as well. A recent study commissioned by skylight manufacturers Velux found that, on average, 63 percent of Americans spend less than one hour outside each day, which can be detrimental to your fitness and cardiovascular health in addition to psychological well-being.

"There's substantial correspondence to SAD occurrence rates and latitude positions in the United States; the rates of people experiencing SAD rise dramatically the further north you go," Greenleaf says. Referencing recent research, Greenleaf adds that just about four percent of the population in Florida experience SAD symptoms year round-that number jumps to about 28 percent of the population for those living in cities in Alaska.

A lack of sunlight can also impact your physical health, says Sudhakar Selvaraj, MD, Ph.D., a psychiatrist with the McGovern Medical School in the University of Texas Health system. Biological reasons point to vitamin D, but other factors also are important. For example, "Sunlight exposure helps convert cholesterol in the skin to vitamin D," Selvaraj says. "Many Americans suffer from low vitamin D which leads to bone, metabolic, and mental health complications, including stress and depression." Experts share how you can use sunlight to your advantage by boosting holistic health functions, including your sleep routine, skincare, and overall mood.

Why Sunlight Influences Your Mood

The reason why sunlight can literally lift your spirits is because exposure increases serotonin activity in your brain; Greenleaf explains that when serotonin counts are lower, there's a higher risk of developing SAD and other mental illnesses. "There's research to suggest that time in the sunshine is a natural drug... sunlight comes through the eyes and gets channeled into the part of the brain responsible for emotional regulation, which then leads to the production of serotonin. Even those who are blind need exposure to sunlight, as they have the same receptors that we do."

For those dealing with SAD, experts often suggest that they invest in what's known as a light box, an appliance that mimics the wavelengths of natural sunlight." A lightbox has been shown to treat SAD and boost serotonin levels, among 75 percent of individuals treating symptoms this way, but Greenleaf says the most light that a light box can produce is capped at 10,000 LUX (or lumens per square meter) compared to natural sunlight, which can reach upwards of 50,000 LUX on a sunny day. Lightboxes can also be uncomfortable to look at for longer periods of time. "Some people may not receive natural light in their homes or workspaces, and they should look into a lightbox; but if you have access to sunlight in the outside world, in your work or living space, you'll reap benefits just by spending time in these spaces and allowing serotonin production to occur."

How a Lack of Sunlight Can Impact Sleep

Dr. Selvaraj says that the body's circadian rhythm and sleep patterns are largely influenced by light exposure, and since sleep has been shown to influence metabolism, it can also have domino effects elsewhere in your health, including your immune system. Beyond serotonin, Greenleaf says that darkness can lead to melatonin production due to our circadian rhythms; it's a naturally-occurring hormone that helps our body regulate our sleep schedule. Melatonin lowers your heart rate and body temperature in order to get you ready for sleep. In sunlight, however, melatonin production is halted. This is why people who work long night shifts often experience mental and physical health issues-our bodies often rely on sunlight to regulate essential bodily functions.

During the winter months, the lack of sunlight throughout the day might lead to surges of melatonin production earlier in the day, which is associated with mood change as well.

When Sunlight Actually Leads to Healthy Skin

Dr. Selveraj says that when people are actively spending time outside or seeking sunlight, the exposure can lead to the synthesis of Vitamin D within the outer layers of the skin. This occurs when immune cells travel outward to repair any slight damage caused by brief exposure to the sun-and published research has shown that sunlight is an important source of Vitamin D for most Americans, especially those with a natural deficiency.

"Sensible exposure to the sun is important-without risking any sunburn, however," Selveraj says. "Depending upon your age and skin color, just 10 to 15 minutes of direct sun exposure three to four times per week is considered best. Avoid excess sunlight by applying sun protection, like a 30 SPF. Vitamin D can also be consumed through a healthy diet or supplements, but always consult a physician before taking supplements."

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