Like a coma?

Some time ago, i started noticing that i fall into some sort of "coma" or trance like state when listening to rather noisy and chaotic music, while i'm tired. i had a problem with this as i'd fall "asleep" in school and would not be able to concentrate or wake up properly. the state starts of with me slipping off halfways dreaming before it gets heavy and black without any dreams. i can wake up but i will not be able to concentrate. does this have anything to do to with the hypnotic techniques i read about here? i tried looking for tutorial on HIT from the glossary but the link was broken.

Sounds to me like Sleep Paralysis. But I dont think this would be possible to achieve during a class at school. Seach for forums for 'sleep paralysis'

Sounds to me like a form of meditation, a deeply relaxed state. I find listening to music has similar effects on me sometimes. It's s similar technique relaxing in a WILD (Wake Induced Lucid Dream) I suppose.