One of the main things that most people want to know is “are there any studies?”

Yes there have been may studies. In this article I’m going to use Adaptogens. Adaptogens? Yup thats right. The term adaptogen is used by herbalists to refer to a natural herb product that is proposed to increase the body's resistance to stress, trauma, anxiety and fatigue. Adaptogens must have the following characteristics:

1. An adaptogen is nontoxic to the recipient.

2. An adaptogen produces a nonspecific response in the body—an increase in the power of resistance against multiple stressors including physical, chemical, or biological agents.

3. An adaptogen has a normalizing influence on physiology, irrespective of the direction of change from physiological norms caused by the stressor.

So basically, natural supplements that are derived from plants, and that have the above characteristics, are adaptogens. For more information please see the following wiki.

From articles on Chiro.org:

In a double-blind controlled study, 36 noninsulin-dependent diabetic patients were treated with Asian ginseng for eight weeks. Patients were given either 100 mg or 200 mg of Asian ginseng or placebo. The ginseng elevated participants' moods, improved physical activity and performance, improved glycosylated hemoglobin, and reduced fasting blood sugars and body weight.

Evaluating the effect of Asian ginseng in various forms--cooked, dried and fresh root--in 1,987 cancer cases, researchers found that the risk of developing certain cancers in a population that used ginseng for at least one year was less than the risk for the general population. The risk continued to decrease with use up to 20 years. In the study, ginseng was found to protect against cancers of the mouth, esophagus, stomach, colorectum, liver, lung, pancreas and ovaries. Thus, the authors conclude that ginseng has a protective effect in most cases of cancer.

In another article:

The objective was to investigate the stimulating and normalizing effect of the adaptogen Rhodiola rosea extract SHR-5 in foreign students during a stressful examination period. The study was performed as a double-blind, randomized and placebo-controlled with low repeated dose regime. The study drug and the placebo were taken for 20 days by the students during an examination period. The physical and mental performance were assessed before and after the period, based on objective as well as on subjective evaluation. The most significant improvement in the SHR-5 group was seen in physical fitness, mental fatigue and neuro-motoric tests (p <0.01). The self-assessment of the general well-being was also significantly (p <0.05) better in the verum group. No significance was seen in the correction of text tests or a neuro-muscular tapping test. The overall conclusion is that the study drug gave significant results compared to the placebo group but that the dose level probably was suboptimal.

Sites of reference:

· http://www.chiro.org/nutrition/FULL/Adaptogenic_Herbs.shtml

· http://www.springerlink.com/content/q361455m3545p06w/

· http://www.medref.se/rosenrot/spasov.pdf