Ashwagandha (Withania somnifera) is a plant that belongs to the Solanaceae family, just like the tomato. It is a herb widely used in Ayurveda, the traditional Indian herbal system. Its roots are used for various therapeutic and medicinal purposes. It is considered a general tonic and an adaptogenic plant, which means that it increases the body's ability to adapt and its resistance to extreme conditions (e.g. cold, stress, physical or psychological demands). One of its effects is to optimise the functioning of the adrenal glands, improving our response to stress. 

It also has the ability to stimulate the immune system, increase energy levels and, at the same time, reduce the excessive production of cortisol. Since excessive cortisol levels are the most common cause of stress-related insomnia, this plant is often used to treat this type of insomnia. In clinical studies, Ashwaghanda has demonstrated anxiolytic effects similar to lorazepan (a drug used to treat anxiety) and has also shown antidepressant effects. 

It has also been recognised as a plant capable of increasing memory capacity and cognitive ability, due to its antioxidant activity and its ability to increase the activity of the acetylcholine receptor (a neurotransmitter involved in memory and learning).  It has also shown very interesting results in Alzheimer's disease. 

Some studies have also reported that Ashwagandha inhibits the growth of cancer cells in animals, but more research is needed to confirm whether these effects apply in humans.