Of all the health benefits of sunlight, initiating the process of producing vitamin D in the body may be the best known. When UVB rays hit human skin, they interact with the 7-DHC protein there to produce vitamin D3.

People can get vitamin D from their diet and supplements, but sunlight is an important source of this essential nutrient. Vitamin D is necessary for key biological processes to take place in the body. Its benefits include:

• supporting healthy bones
• managing calcium levels
• reducing inflammation
• supporting the immune system and glucose metabolism

Researchers have noted a link between exposure to the sun and lower blood pressure levels, with reduced death rates from cardiovascular issues. They suggest that exposure to sunlight triggers the skin to release stores of nitrogen oxides, which cause arteries to dilate, lowering blood pressure, and may reduce the impact of metabolic syndrome.

According to other research, increased sun exposure may also protect people from the following diseases:

• type 1 diabetes
• multiple sclerosis (MS)
• several forms of cancer, including colon, breast, and prostate cancer and non-Hodgkin lymphoma

Sunlight also supports better sleep and sets people’s circadian rhythms by regulating the levels of serotonin and melatonin.

Learn more about the health benefits of sleep here.

Being in the sun generally makes people feel good, and there are many scientific reasons for this effect.

One of these is that exposure to UVB rays causes human skin to produce beta-endorphins, which are hormones that reduce pain. Their other benefits include:

• promoting a sensation of well-being and improving mood
• boosting the immune system
• relieving pain
• promoting relaxation
• helping wounds heal
• helping people feel more alert
• increasing job satisfaction, when a person’s workplace has access to sunlight
• reducing depression

Learn more about the health benefits of vitamin D here

Days without sunshine can be tough for many people, but some individuals find going without the mental health benefits of sunlight more challenging than others. The National Institute of Mental Health say that the following characteristics put people at higher risk of developing depression and seasonal affective disorder (SAD):

• having a family member who has experienced SAD
• a history of depression, attention deficit hyperactivity disorder (ADHD), anxiety, or other mental disorders
• Living far away from the equator

It is also of note that 4 out of 5 people with SAD are female.

SAD is a specific type of depression. The symptoms develop or worsen when the days get shorter, and they improve when the days get longer.

In the northern hemisphere, this means that people with SAD will experience the most intense symptoms in January and February. Researchers say that 1.5–9% of people in the United States may have SAD.

While it is common for people to have spells of the “winter blues,” SAD is a diagnosable condition that can have a significant effect on people’s mental health.

As with other forms of depression, SAD interferes with people’s ability to live their daily lives and causes a low mood that can feel insurmountable. People may lose the ability to find pleasure in activities that they once loved, have difficulty thinking, or feel worthless. They may also notice changes to their sleeping and eating habits.

Both SAD and depression are treatable. Medication and therapy can both be effective, and some interventions harness the health benefits of sunlight.

These interventions allow people to find other ways to access these health benefits, which is particularly important for people who:

• live in parts of the world where there is a significant difference across seasons in the available daylight hours
• work in occupations that keep them indoors for extended periods
• must limit their exposure to natural sunlight for other reasons

Light therapy is a standard treatment for SAD and can be an effective alternative to sunlight. Light therapy regimens, which take place under a medical professional’s supervision, require individuals to sit in front of specially constructed, very bright light boxes for a prescribed amount of time each day. Mental Health America report that light therapy is helpful in 85% of diagnosed cases.

Adjusting light levels and vitamin D intake are not the only possible solutions. Studies have shown that people with SAD can benefit just as much from cognitive behavioral therapy as they can from light therapy.