Although the human mind naturally switches between the different states of mind according to the current environment, situation, people or happenings of the individual, it is possible to artificially stimulate the brain into the different levels. As an extreme example when we are involved in a serious accident or injury, people sometimes enter into coma state. This is the brain's way of performing an emergency response to automatically enter into the deepest realms of delta for heightened physical recovery, trauma protection and mental recovery. This is a very good example of the brain's natural response to a situation where it lowers brainwave activity for instinctual protection means.