Meditation

Here are the EXACT scientific readings for brainwaves:

Beta - normal waking state 15 - 18 CPS(cycles per second)
Alpha - light sleep(light altered state) 8 - 12 CPS
Theta - medium to deep sleep(DEEP altered state) 4 - 6 CPS
Delta - DEEPEST level of sleep, and COMATOSE 0.5 - 2.5 CPS

When you fall asleep at night you cycle from Alpha to Theta to Delta and back. It does this cycle about 8 - 10 times a night and every time the cycle gets shorter until you wake up.

As for stuff like Astral Projection and Telekinesis, Alpha state is all that is required.