Caterpillar mushroom, commonly known as Cordyceps sinensis or "Dong Chong Xia Cao," has a long history of use in Traditional Chinese Medicine (TCM), where it is considered a tonic to improve stamina, vitality, and resistance to fatigue. In the context of "nervous exhaustion"—a historical term encompassing chronic fatigue, burnout, or depletion of nervous energy—Cordyceps has been prescribed to "strengthen the lung and kidney meridians" and to restore overall vitality. Ancient texts and materia medica record its use for symptoms equivalent to what modern practitioners might label as nervous exhaustion, including weakness, fatigue, and diminished endurance. However, scientific validation for these specific effects is limited. While some modern animal and small-scale human studies suggest Cordyceps may help enhance energy metabolism, reduce fatigue, and improve adaptation to stress, these studies generally address endurance and physical fatigue rather than nervous exhaustion per se. There is also some preliminary evidence that Cordyceps may have neuroprotective properties, but this research is in early stages and not directly linked to nervous exhaustion as a clinical diagnosis. Therefore, while traditional use is well-established, scientific evidence remains preliminary, and the strength of support for treating nervous exhaustion is moderate at best.