self medication is how people(like myself) tend to unconciously adjust their lifestyles to try and counter a personal weakness

an example of this is ADD
many many of the ex-hacker/online person category have ADD, and they "coincidentally" also consume a lot of caffiene. this is partly cultural, and partly a function of the fact that stimulants tend to give people who are afflicted with ADD a certain edge in controlling themselves.

other examples:
-the tendency of low self-esteem folks to use certain types of illicit drugs. such as E/X/Ecstasy/XTC, weed, etc.

-the tendency of people with stressful positions to use different illicit drugs, like amphetemines, blow, etc.

anyway, sexual self-medication takes advantage of the endorphin rush that sex brings. you feel good during/after sex.

generally
so persons who feel bad about themselves, or have other problems, can turn to sex much like a drug. it basically keeps you from thinking about anything that may be bothering you, and completely blanks out any feelings you may have. oddly, this is kind of similar to self mutilation. where people hurt themselves in order to drown out a painful feeling with physical pain. or to try and stop a "numbness". it's basically just the opposite pole of the same idea.