Is there a link between constant fatigue and serotonin levels?

I am wondering what is the difference between a steam room and the sauna, is one better than the other? My gym has both and I am interested in trying them out.

What is the best way to prepare, health wise, before a big test such as the SAT, LSAT, MCAT? What foods do you recommend to keep my "brain moving?"

During sex, my husband likes to squeeze and suck my nipples. I enjoy this, but am worried that this type of pressure on the nipples may cause problems later on: we are planning on having a baby in a few years, and I want to breastfeed. Might the pressure of squeezing and sucking hurt my mammary glands and ducts, making it difficult or impossible for me to breastfeed?

1) I've suffered weird digestive things when I have my period. The way I have heard it explained in my MCAT class is that the same hormone that causes the smooth muscle of the uterus to contract unfortunately works on all of our digestive organs as well, particularly the large intestine. So that's how I've come to grips with the apparent confusion of the digestive processes during my period.

2) Does a person's menstrual cycle regulate her bowels in any way? I have had some problems. The week before I get my period, I have loose bowels and the week afterwards I am quite constipated. Is this normal? Is there anything I can do?