Studies on two herbs have shown that they reduce stress, instill calmness and reduce anxiety and depression.  The herbs are rhodiola and ashwagandha.  They have both been clinically studied on humans.  The evidence to support rhodiola indicates that it reduces depression, creates a calm mind, and increases mental and physical performance. 

All herbs are not created equally due to the environment in which they are grown, the contents of the soil, quality of water, sufficient sunlight and a number of other factors, actually even the time that the plant is harvested creates the quality of the plant.  A study of harvesting rhodiola indicated a higher content of key components when it was picked at 5 a.m. rather than 5 p.m.  The name of the herb does not indicate the quality of the herb. 

To get the real benefits of rhodiola and ashwagandha, they should be scientifically studied and the dosage should be verified by the scientific study.  Using both together in a combination formula gives the best results.