Actually, there are many natural states of consciousness. The innermost ones produce a feeling of bliss and fulfillment. One of the aims of spirituality is to consciously 'wade' through the various levels of consciousness and seek the inner most level. This takes a lifetime of rigorous training and guided yogic practice, besides many other lifestyle restrictions.
In this way people manage to discipline their outer mental states slowly over time and then work their way inwards to deeper levels of consciousness. Once this is achieved it is a more or less permanent state and is believed to be a form of liberation from the cycle of life and death.
However, it is possible that through certain drugs, the outer mental states can be temporarily removed so that the person can feel certain blissful states of mind. The mind cannot be controlled through such methods and it results in the outer mental states rebounding back with great force. This results in messing around with the mind and brain, in addictions and severe damage to mental processes.