Question: what are the four different types of brain waves?
Answer: Delta waves (. 5 to 3 Hz) ... 
Theta waves (3 to 8 Hz) Theta brainwaves occur most often in sleep but are also dominant in deep meditation. ... 
Alpha waves (8 to 12 Hz) Alpha brainwaves are dominant during quietly flowing thoughts, and in some meditative states. ... 
Beta waves (12 to 38 Hz) ... 
Gamma waves (38 to 42 Hz)