Your body needs complete darkness in order to produce melatonin, and even then, this will occur only after it has enjoyed some quality sunlight during the day. Melatonin is one of the most powerful antioxidants and has been found key to the prevention of certain cancers - including those attacking the breast and prostrate.Even the tinest bit of light (a nightlight, a streetlight casting a glow through the window) will prevent melatonin production. Sleep in darkness - like everyone did until the last century or so.
As for sunshine, you need it. Not only do the UV rays lessen stress but sunlight acts to reduce blood pressure. Sunlight also acts to reduce death by Multiple Sclerosis by 76% as well as fighting against rheumatoid arthritis and tuberulosis. How? Sunlight causes your body to create Vitamin D, and this nutrient is very important for an effective immune system.
Bottom line: Get one hour of sunlight a day; you can set in the shade on a bright day and this will work. Sleep in total darkness for 8 hours. Simple, free, needed.
Sources: ThomasJeffersonUniversityStudy, Earthtimes.org, mercola.com, AmericanHeartAssociation, mercola.com [citing Lancet].