4 health benefits of sunlight and how much you should get each day
- Small doses of sun exposure can provide health benefits, such as boosting mood and increasing vitamin D production.
- For most people, 10 to 15 minutes of sun exposure a day is enough to receive these health benefits.
- To prevent sun damage and minimize health risks, you should wear broad spectrum sunscreen daily with at least an SPF of 30.
- This article was medically reviewed by Benjamin Bert, MD, an ophthalmologist at MemorialCare Orange Coast Medical Center in Fountain Valley, California.
Sunlight is often perceived as a threat to your health because it can cause wrinkles, premature aging, and most importantly, skin cancer. But, research suggests exposure to sunlight may actually be beneficial in small doses.
Here are a few ways sunlight positively affects your body and brain, and how much sun you should get to receive these health benefits.
1. Sunlight boosts mood
Scientists have found that sunlight may affect the central nervous system's functioning — primarily in regards to serotonin levels.
Serotonin is a neurotransmitter and hormone secreted by the hypothalamus that allows brain cells and other nervous system cells to communicate with one another.
It plays various roles in our sleep and eating habits, but it's perhaps best known for its effect on mood stabilization, feelings of well-being, and overall happiness.
Because sunlight helps the body release serotonin, during periods of the year when sunlight is less available — like in winter — the hypothalamus produces less serotonin from sunlight. This can put people at an increased risk of experiencing symptoms of depression and anxiety, possibly leading to conditions like Seasonal Affective Disorder (SAD).
SAD, or seasonal depression, is a mood disorder that manifests during fall and winter months. Those who experience SAD usually see their symptoms of depression improve come spring and summer with more daylight hours. One of the ways the disorder is treated is with artificial light, as the practice is believed to boost serotonin levels.
2. Sunlight increases vitamin D production
Sunlight serves a crucial role in the body's production of vitamin D, which has many health benefits. Vitamin D helps your body absorb calcium, as well as to mineralize. Mineralization describes the formation of bone matrix, which makes bones strong and rigid.
Sunlight is the primary way people get vitamin D.A common misconception is that sunlight actually contains vitamin D. In fact, UV rays in sunlight stimulate the skin to produce the substance.
Research has shown that maintaining adequate amounts of vitamin D may protect you from developing multiple sclerosis and various forms of cancers including ovarian, breast, and prostate.
It is important to note these studies all found correlations, not causations in the connection between vitamin D and cancer. Therefore, there is no guarantee that adequate amounts of the sunshine vitamin will prevent cancer.
Further, using sunscreen daily will not eliminate the amount of vitamin D benefits offered by the sun.
3. Sunlight may prevent nearsightedness
Research suggests children who spend more time in sunlight may be less likely to become nearsighted. A 2012 review published by the American Academy of Ophthalmology found that for each hour children up to the age of 20 spent outdoors, the odds of developing nearsightedness fell 2%.
Christopher Starr, MD, an ophthalmologist at Weill Cornell Medical College, says kids should spend an additional one to three hours a day outside, to stimulate dopamine production. Lack of dopamine causes elongation of the eye, resulting in nearsightedness. However, exposure to sunlight does not seem to reverse the effects on kids who are already nearsighted.
4. Sunlight can help you sleep
Sunlight plays a pivotal role in regulating our internal clock. This clock, otherwise known as circadian rhythm, dictates our behavior based on time of day — like when to fall asleep, wake up, or eat. Light appears to be one of the main driving forces behind this clock.
Through a process called entrainment, a person's circadian rhythm needs to reset every day in order to stay synced with changes in light. This can occur because of changing seasons or moving to a new time zone. Research indicates entrainment takes place as a result of exposure to light and darkness.
Regular exposure to sunlight trains your brain to sleep when it becomes dark, and as a result, it can help you get a better night's sleep.
How much sunlight should you get?
According to Adam Friedman, MD, professor and interim chair of dermatology at the George Washington University School of Medicine and Health Sciences, it's difficult to determine a standard amount of time one should spend soaking up the rays to ensure adequate vitamin D production.
For many people, 10 to 15 minutes of sun exposure per day is enough. However, the length of time will vary widely due to factors like skin color, elevation, and how close you are to the equator.
In much of the US — that is anywhere roughly north of Arizona — the skin produces trivial amounts of vitamin D during fall, winter, and spring. Meanwhile, people over the age of 65 produce just 25%of the vitamin D that young adults do. Black people also do not make as much vitamin D, as darker skin pigmentation reduces production.
Therefore, Friedman recommends people who fall into the above demographics take vitamin D supplements. The standard dose for adults under the age of 70 is 600 international units (IU) a day.
In rare cases, taking too much vitamin D can lead to toxicity called hypervitaminosis D, which can lead to renal and cardiac problems.
Too much sunlight can be harmful
Spending too much time in the sun can be harmful to your health. Even the mildest sunburn is considered a skin injury. Other skin conditions like hyperpigmentation, wrinkles, and sun spots are also caused by too much UV radiation.
Of course, these concerns are far from just cosmetic. Skin cancer, often caused by harmful ultraviolet radiation, is the most common form of cancer in the US with more than 9,500 people diagnosed every day. This is why it's important to wear sunscreen regardless of how much time you spend in the sun.
"We do recommend everyone should wear sunscreen, SPF 30 or higher broad spectrum on exposed areas every day," says Friedman.
For more information, learn about how to protect yourself and treat sunburn.
The bottom line
Sunlight provides a wide range of health benefits. Even just 10 to 15 minutes of daily exposure can jumpstart production of vitamin D and regulate your sleep schedule. But, too much sunlight can cause adverse health effects like skin cancer. That's why it's important to wear sunscreen daily.