Ashwagandha is known as the "ayurvedic" ginseng. It is indicated for the same types of conditions as ginseng, but Ashwagandha is not heating, Yang, or stimulating like ginseng.
It is used preventatively for those who put out more energy than they put back into themselves and want to avoid burn out and break down.
It helps immunity to self modulate. It also has an affinity to help chronic neuro-muscular disorders such as fibromyalgia and multiple sclerosis.