According to experiments done by the experts of London University medical center in Holland, rats are kept in natural light (Sun) and then in artificial light (bulb etc.) but they are not kept in darkness, this procedure continued for many months then it is came to know that the brain of rats badly effected and their bones and muscles being weak. While rats rapidly becoming the victim of germs and immune system of their body also being weak.
According to experts as rats kept under light and darkness as per routine than rats being healthy after two weak and health going better it proves that dimness is also very important for humans.
It is saying of experts that the duration of light and darkness in twenty four hours has much importance for humans because it keeps correct the internal clock of man.
Experts has expressed the concern that the seventy five percent population of the world lives in the boundary of artificial lights at night time and by this their health is effecting. Similarly nurses and doctors working in hospitals and working members at night remain in artificial lights till day and night and by this their health can be provoked.