Sun gives life to everything on the Earth. Without sun, plants will not be able to grow. Plants produce oxygen,  which allows animal to survive.  Without oxygen, the current life as we know it will not exist. But lately, there is a movement to demonize the sun as a cancer-causing monster. Let’s look at the role of the sun in human physiology to get the answer.

Everything on Earth is cyclical, we have seasons, day and night, etc. The same applies to humans. Our function is governed by circadian rhythms. Every cell in our body has a, so called, clock gene, which basically controls functions of the cell, depending on the time of day. Humans get information about time from the sun (sun clock anyone), not from fancy Apple watches or smartphones. Our eyes are not only created for vision but also serve as a time control mechanism.

Our eyes are connected to suprachiasmatic nucleus  in the brain that
is responsible for generating circadian rhythms. It decodes the light
color spectrum signals generated by our eyes and responds by turning
certain clock genes on/off and relaying these circadian rhythms
throughout the body.

For example, our body does not release melatonin during the day
and this is related to the composition of light that is penetrating our
atmosphere in the morning (equal parts of blue light and red light). In
the evening, when red light from the sun predominates, our body releases
melatonin and we fall asleep. This is what is supposed to happen,
except that now we shine blue light in our eyes all the time by using
smartphones, TVs, computer screens and LCD/fluorescent bulbs. This
incorrect light composition confuses the body’s clock genes and
eventually lead to chronic disease

Exposure to sun generates vitamin D in our body. Every cell in
our body has vitamin D receptors, suggesting a profoundly important role
of this hormone (yes, it is a hormone, not a vitamin). Vitamin D
deficiency has been linked to numerous chronic diseases, including
strokes, dementia, and cancer. Proper exposure to sun assures correct
levels of Vitamin D, proper immunity and correct function of the body.

Sunscreens block formation of Vitamin D and then we wonder why everybody is deficient.

As you can see in this brief introduction, sun is important to
our physiology. But proper sun exposure is vital and it a part of my
coaching program.