Sun exposure, good or bad?
In the last years sun exposure has been demonized due to data that links sunburns to cutaneous malignant melanoma (CMM), however, it is important to note that this information is based on sunburns not sun exposure.
If we are going to be exposed to the sun for a long period of time (more than 30 min), it is recommended that we protect our skin to avoid sunburn (sunburn can be defined as a blistering of the skin or pain on the skin lasting +2 days caused by exposure to the sun), however, getting some sun exposure on a daily basis has shown to be very beneficial for our health.
Here are some of the many benefits:
Exposure to the sun can protect us from Cutaneous Malignant Melanoma (CMM)
Contrary to the belief that sun exposure without sunburn may increase our risk of cutaneous malignant melanoma (CMM), some studies suggest that chronic, low-grade exposure to sunlight may be protective against it (6). In one Austrian case-control study, those with chronic sun exposure without sunburn had a reduced incidence of CMM compared with those with recreational sun exposure. (1)
A study by Jason K Rivers states that ‘…outdoor workers have a decreased risk of melanoma compared with indoor workers, suggesting that chronic sunlight exposure can have a protective effect’ (2). In Germany, outdoor activities during childhood, in the absence of sunburn, were associated with a lower risk of melanoma. Chronic, repeated sun exposure may allow the skin to protect from UV radiation by increasing melanin production, thus reducing the risk of sunburn (3). An English study published in 2011 showed that regular weekend sun exposure in warmer months had a protective effect against CMM. Serum vitamin D levels were strongly associated with increased weekend and holiday sun exposure (4).
Sun exposure is the best source of vitamin D we have
A good vitamin D serum level is one of the most powerful weapons we have to prevent cancer. Our body converts vitamin D in calcitriol, the hormonal version of vitamin D, which our body utilizes to repair cellular damage, or in the case of cancer cells, to cause apoptosis (cell self-destruction). A level above 32 ng/ml of vitamin D in our body, considered optimal by some researchers, can help us prevent more than 16 different types of cancer, including pancreas, lung, ovaries, mama, prostate and skin. Joan Lappe and Robert Heany did a 4 yrs controlled, double blind, randomized study in 2007 where they supplemented a group of 1179 women age >= 55 yrs with calcium and vitamin D and they could reduce the risk of breast cancer in 77% (5).
Sunlight exposure helps us to sleep better.
The sunlight helps us regulate our circadian rhythm. The daylight gets into our eyes through the optical nerve, sending a signal to the suprachiasmatic nucleus (SCN), which is very sensitive to the light and darkness cycles, these cycles are vital for the right functioning of the circadian rhythm, term used to define the group of physical, mental and behavioural changes linked to the transition between day and night. In the absence of light the SCN tells the pineal gland to produce melatonin, this hormone plays a key role in the regulation of the circadian rhythm helping us to sleep and to control the time in which we are sleep and awake.