So I started sungazing in 2003, and did it pretty regularly for about a year or so. I even got to the point where I was sungazing at noon in the tropics.
Positive effects included kidney cleansing, nasal cleansing, tear duct cleansing, etc.. It's very good for detox. It also gives a short-term boost in energy, and is good for reducing anxiety, IME.
One day I decided to see if I could fast for an extended period without losing weight. I had read a good bit about the potential for people to survive on very little food while doing a lot of sungazing, and I had a lot of experience with fasting, so I knew I could fast safely for several days. I drank a lot of water, and sungazed intensely the whole day. The end result was that I got pretty nauseous. Ever since then I get nauseous if I sungaze very much.
I still enjoy it in small amounts, though. It really does do wonders as far as nasal and tear duct cleansing.