Posted by Larry Hoover on April 12, 2009, at 12:21:00
In reply to Re: Question about sunlight,UV rays,depression etc., posted by odon on April 12, 2009, at 11:26:49
Why don't you provide a link to the article(s) you're referring to, so we can assess their content in a more deliberate way?
I'm having trouble finding any support for your thesis that UV light impinging on the eye is a good thing. The human cornea is virtually opaque at UV wavelengths, and cumulative exposure damages the cornea by forming cataracts. Not all contact lenses absorb UV light, and of those that do, none do so as well as the cornea behind them.
There are specific receptors on the retina tuned to blue-light frequencies, as mentioned by others. Artificial light is typically not very powerful at these frequencies, perhaps at best reaching only 10% of the intensity found in the noon-time shade outdoors. So, there certainly is both a spectral and intensity difference between artificial light and sunlight. Here's a nice full-text review article of the impact of light filtering on humans: http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=18757473
As to skin exposure to UV light, and the use of sunscreen, that is a different story altogether. There is a delicate risk/benefit balance at play that can only be applied on a case-by-case basis. There is no generalized good/bad recommendation to consider.
Lar
poster:Larry Hoover
thread:889657
URL: http://www.dr-bob.org/babble/20090408/msgs/890124.html