Researchers from the around the world found that levels of serotonin—a neurotransmitter that regulates appetite, sleep, memory, and mood—are lower during the winter than the summer also, patients undergoing surgery who were placed in bright rooms reported less perceived stress and took less medication per hour than patients in dim rooms. Studies also suggests that even indirect exposure to sunlight can improve one’s mood. Other Studies have linked vitamin D, known as the “sunshine vitamin,” to the protection against colon, kidney, and breast cancer. It’s also linked to improvements in bone health and overall mortality. Neurological, cardiovascular, and immune diseases are associated with vitamin D deficiency. By increasing your exposure to sunlight, you can decrease your risk for these diseases.
In the other side, sunlight exposition also can be bad, It is well known that exposure to ultraviolet (UV) radiation present in sunlight is responsible for a lot of cases of skin cancer in humans. Wavelengths in the UV-B (290–320 nm) region of the solar spectrum are absorbed into the skin, producing burns, and eventually skin cancer. Skin cancer is the most common type of human cancer.The question is how to get the benefits of the sunlight without the exposure to the UV-B rays?
Coeluxs, may have the solution.
CoeLux is an optical system based on nano technology to artificially reproduce the natural light and visual appearance of the sun and sky, offering a breakthrough opportunity for indoor architecture by creating the sensation of infinite space.
The CoeLux skylight system utilizes elements to emulate natural lighting. They incorporate select LED lighting to closely resemble natural light and the sun. The team then developed a complex optical system which emulate the sun and its rays using nano-structured materials to recreate in just a few millimeters the same Rayleigh scattering process that occurs in the atmosphere. A clear cloudless day-time sky is blue because molecules in the air scatter blue light from the sun more than they scatter red light. When we look towards the sun at sunset, we see red and orange colours because the blue light has been scattered out and away from the line of sight.

In order to achieve a 3D effect and reproduce natural sunlight, CoeLux team had to develop a photo realistic rendering engine that is capable of simulate sky sunlight working with select materials.
Coelux can be be programmed to emulate three different geographic lighting scenarios, such as northern Europe for example, where the light runs at a lower angle relative to the horizon than at the equator
A more detailed project summary of the CoeLux system can be viewed at the European Commission's CORDIS portal.