Sunlight is essential for human health, but spending too much time under strong ultraviolet (UV) rays can increase the risk of skin cancer and other health problems. Experts say the key is finding a balance between getting enough daylight and avoiding prolonged, unprotected exposure.
Short Exposure Can Support Health
Rebecca Mason, Professor of Physiology at the University of Sydney, says vitamin D production is most effective when people get short, regular periods of sunlight rather than staying outdoors for long periods.
Vitamin D helps maintain healthy bones and muscles and also plays an important role in the immune system. The amount of sunlight required can vary significantly depending on skin colour, location, season and the amount of skin exposed.
People With Darker Skin May Need More Sun
Lesley Rhodes, Professor of Dermatology and Photobiology at the University of Manchester, says the balance between the benefits and risks of sunlight differs according to skin type and colour.
People with darker skin have more melanin, which provides greater protection against UV-related damage. However, the same protection can mean their bodies need longer exposure to produce sufficient vitamin D.
Research cited by experts suggests that people with dark brown skin may need considerably more midday sunlight than people with lighter skin to generate similar amounts of vitamin D.
Morning Light Can Improve Sleep
JoAnn Manson, Professor of Medicine at Harvard Medical School and Brigham and Women's Hospital, says only small to moderate amounts of sunlight are needed for good health.
Daylight also helps regulate the body's internal clock. Morning light signals to the brain that it is daytime, helping regulate hormones linked to alertness and sleep. Regular exposure to daytime light has also been associated with better cognitive performance and a lower risk of some health problems.
Too Much Sun Can Be Dangerous
While moderate exposure can provide benefits, prolonged exposure to UV radiation can damage skin cells and increase the risk of skin cancer. Excessive sunlight can also contribute to premature skin ageing and eye problems such as cataracts.
Experts particularly urge caution for people with very pale skin, many moles, a personal or family history of melanoma, or those taking medicines that suppress the immune system.
Children and teenagers also need strong sun protection because significant UV exposure early in life can increase the likelihood of developing skin cancer later.
Winter Sun May Not Be Enough
In regions with weak winter sunlight, the body may struggle to produce sufficient vitamin D naturally. People who spend little time outdoors or have darker skin can be at greater risk of vitamin D deficiency.
However, experts stress that sunlight is not the only way to maintain healthy vitamin D levels. Depending on individual circumstances, dietary sources or supplements may help.
The Main Advice
The overall message from experts is simple: short and regular exposure is preferable to prolonged sunbathing. People should avoid getting sunburned, protect their skin when UV levels are high and wear sunglasses that provide adequate UV protection.
The amount of safe sunlight is not the same for everyone. Skin type, age, location, season and UV intensity all matter. Rather than seeking a deep tan, experts recommend getting enough daylight for its potential health benefits while taking sensible steps to reduce UV damage.