"Keep your face to the sunshine, and you cannot see the shadows," Helen Keller once said. And while Keller's words might oversimplify the matter, you do need sunlight to maintain optimum health and wellness. Sunlight can influence brain health, sleep, immunity, healing, and even intimate desire.
The health benefits of sunlight mostly come from vitamin D, a crucial element human beings soak in during sun exposure. Without enough vitamin D, the body cannot operate at its best. According to the National Institutes of Health, those at highest risk of vitamin D deficiency include breastfed infants (human milk alone contains an insufficient amount of vitamin D), older adults, people with darker skin - and anyone with limited exposure to the sun.
If you're (literally) in the dark, your body might exhibit less-than-sunny symptoms.
Exposure to sunlight encourages the natural production of vitamin D. Sun exposure is the fastest and most effective means of boosting vitamin D levels, but vitamin D is also available through certain foods, such as oily fish, dairy products, egg yolks, and beef liver. Even in these nutrient-dense foods, however, the amount of vitamin D is still relatively low, so achieving optimal levels through diet alone is virtually impossible.
When you don't get enough sunlight, vitamin D deficiency is a common result.
Vitamin D levels are directly linked to mood. Numerous studies have confirmed this connection, which researchers say is related to the abundance of vitamin D receptors in the brain. In general, the lower your vitamin D levels, the more likely you are to become depressed.
Seasonal affective disorder (SAD) is an associated health condition that can affect even those not ordinarily prone to depression. SAD usually strikes during the winter months among populations who live in areas with infrequent sunlight. The disorder is characterized by many of the same symptoms as clinical depression.
A lack of sunlight can also wreak havoc on the body's metabolic system. Nitric oxide, produced by nearly every kind of cell, is an essential component of a healthy metabolism. Sunlight promotes the production of nitric oxide, so when sun exposure is limited, your body can't metabolize fat as efficiently as it usually does.
Studies have also found that weight gain due to vitamin D deficiency is a risk for women above age 65.
Low vitamin D levels might be linked to an increased risk for certain types of cancer. Staying out of direct sunlight and wearing sunscreen can help prevent skin cancer. On the other hand, however, studies also suggest sun exposure and higher levels of vitamin D can prevent or slow the growth of cancer cells, stimulate cell expiration, and reduce the formation of blood vessels in tumors.
Other studies have found that people who live in southern latitudes - where the sun is brighter and shines more consistently - have a lower chance of developing certain kinds of cancer.
However, experts say people need to find a balance between getting enough sun and taking precautions to prevent sunburn and skin cancer.