Why is sex never counted or studied as an altered state of consciousness? The description and transition between everyday reality to erotic reality (Davis) is no different from any other altered state of consciousness!
Consciousness is always there as background and we have world presented as noise in foreground. State of Consciousness needs to be acknowledged and appreciated in every moment of life not just in sex. I agree that it is no different but we cannot have sex all the day ! ! ! ! ! ! !
I have also been interested as to why sex, and sexual play has not been more thouroghly researched as a natural form of altering consciousness. One article I did find to be of interest is -
_ Zussman, (1998) Shifts of Consciousness in Consensual S/M, Bondage and Fetish Play. Anthropology of Consciousness, 9, 15-38.
Perhaps you've already read it, I found it to be interesting, and Zussman is one of the only researchers that I have found (so far) that deals with the topic.