Pratyahara and chemicals.

Pratyahara:
For Patanjali, it is a bridge between the bahiranga (external) aspects of yoga namely, yama, niyama, asana, pranayama, and theantaranga (internal) yoga. Having actualized the pratyahara stage, a practitioner is able to effectively engage into the practice ofSamyama. At the stage of pratyahara, the consciousness of the individual is internalized in order that the sensations from the senses of taste, touch, sight, hearing and smell don't reach their respective centers in the brain and takes the sadhaka (practitioner) to next stages of Yoga, namely Dharana (concentration) and Dhyana (meditation), and Samadhi (mystical absorption), being the aim of allYogic practices.^[3]

          Never liked the idea of withdrawal of the senses. Sounds like death to me. Things closing down. Diminishment.
           I'm  a bit wary to taking serotonin enhancers with the bliss being the way it is. It must have a physical base in the hormones, chemicals, electricals and whatnot, and I assume it must have something to do with receptor, inhibitors, neurotransmitters and whatnot. And that's what the serotonin enhancers do as well. So you think you maybe should dodge that one.
             Hotboy, you should have dodged the fags and the acid and the drink and the speed and all that stuff, but you didn't, did you? Well, Jack, I don't dodge it so well these days either.
             The first time I sat down on the carpet and closed my eyes and there was the bliss as usual. Then everything went bigger and the voices around me started to grow distant and I couldn't properly communicate at all, and the bliss ... Oh, ra bliss, ra bliss, ra bliss!
              When the senses diminish in this instance, the consciousness expands wonderfully. There is no minimisation, or diminishment. It's big, big but you're kind of on your own what with being effectively deaf to the world.
                This happened again last week.
                 I don't know if this is a hint of pratyahara or not. The above definition isn't really what I take it to be, but what do I know?
                  In tantric terms the winds are supposed to be entering the central channel. When this happens and the winds stabilise and whatnot, you are supposed to go into something akin to death. This removal of senses, in the way I was talking,  is a wee bit scary because you do feel as if you are going away. Bye bye, world. Also when you die the bardo is supposed to start with you being in a huge, lonely limitless space. Well, good luck with that if that's what happens.