(Post by Tim Desmond who hosts a website offering phone counseling and information on treating depression.)
Light therapy (also called phototherapy) has been studied as a treatment for seasonal depression for more than 20 years. More recently it has been shown to be one of the most effective treatments for nonseasonal depressional as well. Several studies have shown lightboxes can achieve significant relief from depression more than four times faster than medication. It is estimated that a significant percentage of people in the US suffer from light deficiency. Symptoms of light deficiency include depression, lack of motivation, lack of energy and carbohydrate craving.
What kind of light to use
Both natural sunlight and commercial lightboxes have been shown to treat depression effectively. While there is some evidence that exposure to light in the early morning is most effective, other studies suggest that different people respond best to getting light at different times of day. Average exposure time in most studies to a 10,000 lux lightbox (lux is a unit of brightness) was thirty minutes. If choosing to use sunlight, thirty minutes on a clear day at midday is ideal. Commercial lightboxes and the sun can both produce vitamin D, which is believed to play an important role in causing and treating depression. However, the sun can only do so when it is high enough in the sky for UVB rays to penetrate the atmosphere. Depending on your latitude, the sun may only be high enough in the sky to be able to produce vitamin D for a few hours around midday.
Whether you choose natural sunlight or a lightbox, it is very important that you do not use any sunscreen. Sunscreen blocks your body's ability to produce vitamin D. If you believe your depression might be caused by a vitamin D deficiency, you should also take a vitamin D supplement.
Ray, your information on light therapy ofr deporession is incorrect and misleading.
Please, do some reading on this subject before you offer advice.
One example - all commercial light therapy units used to treat depression screen out all UV in order to protect the eyes, and therefore cannot produce virtamin D.
another example - The taget of light therapy treatment for depression is to stimulate a pathway that originates in the retina, not the skin. Wearing sunscreeen will not affect the stimulation of this pathway at all, as the light has to enter the eye to reach the retina.