I read in wikipedia that William Bates said that we should look directly at the sun. That exercise was then changed to sunning. Could sunning also cause cataracts? ???
Don't read wikipedia on such controversial topics.
I wouldn't suggest staring directly into the sun. There is a technique that does this, but it must be done THE RIGHT WAY, as you may do more harm than good. Read the Bates book on the proper way to do sunning, he describes it much better than I can. He also addresses how you should look into the sun, but please use caution, or stay away from that part all together. I suggest performing this technique with closed eyelids.
The "Better eyesight without glasses" book is available for free on this website, and the topic is on page 199.
There are also many references to it throughout the book - the fact that you can use it to enhance your imagination of a black period. I always like to do palming right after sunning.
Looking at the sun with closed eyelids cannot cause cataracts because the eyelids filter out all of the UV radiation, but looking at the sun with open eyelids may - though highly unlikely for two reasons. At your age nobody gets cataracts, and its more for prolonged exposure to UV radiation while working outside for very long periods of time - weeks, months.
I've heard of people using spotlights. Anything else and you'd need to do it eyes open to really get any benefit. I've never understood the idea of sunning with a regular light bulb that some Bates teachers recommend - it's such a small amount of light when your eyes are closed, not intense at all.