Introduction
This herb is used for 4000 years plus in India. It is a very important herb in ayurveda, the traditional Indian medicine. It is used for tumors, inflammation including arthritis), and a wide range of infectious diseases. The shoots and seeds are also used as food and to thicken milk in India. In Ayurvedic medicine, this herb is considered the "Ginseng of India", said to "protect the organism from illness through maintaining the healthy balance of physical energies." Like other adaptogens, ashwagandha root exhibits an anti-stress effect, an immunomodulatory effect; it can enhance both short and long term memory.

Origin
It is distributed in drier parts of India upto 5,500 m. The plant is widely distributed in North-Western India, Bombay, Gujarat, Rajasthan, Madhya Pradesh, Uttar Pradesh, Punjab plains and extends to the mountain regions of Himachal Pradesh and Jammu. The plant is distributed throughout the drier subtropical regions of India. Not common in Kerala. The plant is also recorded to occur in Mediterranean (Israel), Canary Islands and Cape of Good Hope.

The principle constituents of its roots Compounds known as withanolides are believed to account for the multiple medicinal applications of ashwagandha.These molecules are steroidal lactones with erggostane, which (include withanone, withaferin, withanolides, withasomidienone, withanolide C and alkanoids about 0.2 %) and bear a resemblance, both in their action and appearance, to the active constituents of Asian ginseng (Panax ginseng) known as ginsenosides.

Roots of the plant show antitumor and radiosensitizing effects in animal model.Total alkaloid fraction of the root extract exhibit hypotensive bradycardic and respiratory stimulant activities in dogs. It shows relaxant and antispasmodic effects against several plasmogens on intenstinal, uterine, bronchial, tracheal and blood vascular muscles. Withanolides possess remarkable antibacterial, antitumor, ant arthritic and immunosuppressive.

Ashwagandha has been found to have important healing effects on solid tissues, skin support, connective tissue, lymph tissues, blood vessels, and mucous membranes. Ashwagandha has found its most successful applications in treatment of conditions involving venous insufficiency, tissue inflammation and infection, and post-surgical healing. Taken together, these actions support the traditional reputation of Ashwagandha as a tonic or adaptogen. It counteracts the effects of stress, headaches and generally promotes wellness.
Other benefits are for:
Arthritis & Parkinsons, Hypertension, Diabetes, General debility.
 

References:
1. Devi PU, et al. In vivo growth inhibitory effect of Withania somnifera (ashwagandha) on a
    transplantable mouse tumour, Sarcoma 180. Indian J Exp Biol 30: 169–172, 1992.
2. Al-Hindawi MK, et al. Anti-granuloma activity of Iraqi Withania somnifera. J Ethnopharmacol 37:    113–116, 1992.
3. Kuppurajan K, et al. Effect of ashwagandha (Withania somnifera Dunal) on the process of aging in    human volunteers. J Res Ayurveda Siddha 1: 247–258, 1980.