Astral is when you "fly" (if you will) out of your body and go to talk to ppl you've most likly never met or when your making sure someone you know is ok, this mostly happends when you sleep, you can msg me to learn more.
Actually, it doesnt happen when your sleeping. Its when you put your body to sleep but keep your mind awake. Basicly your body goes numb, vibrations begin and you have to float, pull, roll etc. out of your body. Everybody sees the Astral differently, so I'll let you firgure that one out on your own ;)