The notion of psychedelic drugs is a convolution of terms, not very surprisingly, considering the adverse effects drugs have on the users who'd describe the effects. Huxley used LSD for example.
The term you are looking for is trance. Think of those manic church sessions, where people feel all so connected to god and go stark raving mad. Psychedelic trance can be achieved playing music or through meditation, as well.
Soma is described as being able to take a few grams and experience an eternity of time within a few hours. It sounds more like an intense psychedelic.