An article by Paramhansa Yogananda.

The main causes of nervousness are 1) long-continued over-activity, 2) excessive stimulation of the senses from physical over-indulgence, 3) and mental over-stimulation from chronic fear, anger, sorrow, hatred, jealousy, discontent or similar harmful emotions.

Any violent or prolonged excitement disturbs the flow of life force through the nervous system.…