Most people are aware that for many, wintertime means severe depression. For a long time, people had no real idea why this happens. There were clues, though. The depression is greater for people living a greater distance away from the equator than for those living closer to the equator.
Finally, a few people began to ask if there could be a connection between moods and sunlight. After all, that is the common denominator. In winter, the greater your distance is from the equator in the winter, the less sunlight is received. If a connection could be made, it would be a great step forward in proving that sunlight affects our lives in profound ways.
Tests on the hypothesis were pretty simple. Take a group of people most likely to become depressed in the winter and subject them to a couple hours of sunlight, produced with light bulbs that gave off the same spectrum. Compare this with a similar group who received regular fluorescent or neon lighting, and a third group who received no special lighting at all.
The results were surprising to many. Those receiving the artificial sunlight tended to be cheerful all through winter, regardless of the latitude of their position. There was no change in those in the two control groups. Though still far from conclusive, it did appear that sunlight had an effect on mood.
This led other scientists to begin to speculate that among other things, sunlight may have a major bearing on our biological clocks. In essence, they started wondering if 'jet lag' could be caused by sunlight or lack of it, and the times we are exposed to it. Through similar tests to those above, they found a correlation. People traveling from one time zone to another that was quite a bit different, could be 'cured' of jet lag by exposing the person to artificial sun rays for an hour a day prior to the trip and at the time of normal sunrise in the location they were going to.
For instance, someone on the west coast of the US going to the east coast of the US, a difference of three hours, when subjected to an hour of sunlight three hours earlier than what they'd experience at home at sunrise, suffered little or no jet lag.
There are many more studies going on now. However the point is that sunlight affects our lives in many ways, and some of those, we are just learning.
We've known for years that having some sun helps our bodies. It isn't just cosmetic as in suntans, or all harmful as in sunburn or skin cancer. In fact, as surprising as it may be for some, the previously mentioned studies are showing that some sun on the skin may actually help prevent skin cancer. (Like anything else, it can be overdone. Moderation is the key.)
We can even get to a more basic level. The amount of sunlight and darkness we get each day has a huge impact on our biological rhythms. For instance, people living in the north often find that they have less energy in the winter than in the summer. This stands to reason since when it is dark; our minds tell us that it is time to sleep. If there are more hours of dark than light, it would make sense that we don't have as much or as many hours of energy.
Thankfully, the studies already mentioned have shown a potential way to overcome a lot of this, and businesses and schools are already using it.
It is important to understand that not all effects of sunlight are positive. This has already been mentioned, but excess sun can have an adverse effect. Fair skinned people or those who work outdoors should take precautions to avoid sunburns. These are not only painful, (which in itself effects your life due to lack of movement or desire to move), it kills skin cells. The body's resistance drops since more of the immune system is put into play to repair the damage. Skin is an organ, and the largest of the body. Damaging it takes up an enormous amount of work for the body to fix the problem.
Sunlight affects a far larger part of our lives than most people are aware. It produces heat and keeps the earth from freezing, but the effect of sunlight on our lives is a lot more complex than we once thought. Like everything else about this planet, it appears that we are in for a great number of years learning, and even then, it's doubtful we'll know all the effects of sunlight on our lives, or that of any other creature on Earth, for that matter.