I took an Ambien once so I could experience a vegetative state!
"...No one yet knows exactly how a sleeping pill could wake up the seemingly dead brain cells, but Nel and Clauss have a hypothesis. ... during [PVS] the receptors are in some way changed or deformed so that they respond to zolpidem differently from normal receptors, ... it makes dormant areas of the brain function again and some comatose patients wake up."
I always thought that giving a hit of speed to someone in a coma from OD'ing on sleeping pills would have the same effect.