orgasms effects on women's mood

i'd think so but the problem is women are quite psychologically involved in their ability to have orgasms. by this i mean stress and mood can make them unable to orgasm in the first place.

Yes, this can happen, just like it can happen for men. An orgasm feels good, and this is one reason some people masturbate specifically to relax or release tension. Sometimes, this will lead to great mood improvements, but it isn't a fail-safe. 

Another thing to keep in mind is that a woman's orgasm may not come at all if she feels excessively stressed, though. This depends on the woman. Certainly, many women are not going to feel in the mood for sex with a partner if they feel angry or upset with their partner for instance. Don't suggest "can I give you an orgasm" as a way to make her feel better when she is upset because that probably won't work at all. :)