Vitamin D: effects on human health

Ultraviolet radiation -
Sunlight reaches the Earth in the form of ultraviolet (UV) radiation. Sunlight has both positive and negative health effects.

Vitamin D -
The UV in sunlight is a principal source of vitamin D. When your skin is exposed to sunlight, it makes vitamin D from cholesterol. 

Calcium and phosphate levels -
Vitamin D helps regulate the amount of calcium and phosphate in the body. These factors are vital for maintaining healthy bones and muscle. 

How much sun? -
The World Health Organization (WHO) states that five to 15 minutes of casual Sun exposure of hands, face, and arms two to three times a week during the summer months.

Sleep-wake cycle -
Sun exposure is associated with the timing of melatonin synthesis. Melatonin is a hormone that regulates the sleep–wake cycle. 

"Winter blues" -
Sometimes referred to as the "winter blues," SAD has been linked to a biochemical imbalance in the brain prompted by shorter daylight hours and less sunlight in winter.

Depression -
If you’re a woman, it is 200% more likely that you will develop SAD than the average male, according to studies. 

Dangers of long-term exposure to sunlight - Long-term sunlight exposure is known to be associated with a number of negative health issues.

Skin cancer -
Skin cancers are cancers that arise from the skin, and more than 90% of cases are caused by exposure to UV radiation from the Sun.

Dark-skinned? -
Dark-skinned people still need to adopt caution under strong sunlight. 

Skin aging - Overexposure to the Sun is associated with the development of skin aging, a process technically termed photoaging. 

Photosensitivity -
A small percentage of the population have a skin condition that makes them particularly sensitive to the Sun's UV rays. 

Snow blindness -
Bright sunlight can induce snow blindness, or photokeratitis.

Lack of sunlight can impair a child's vision - Children who spend more time outside reduce their risk of myopia, or nearsightedness.

The sunniest place on Earth -
According to the World Meteorological Organization, Yuma (pictured) in Arizona is the sunniest place on Earth. 

Click Here