Since stress levels are associated with neuroendocrine function, ashwagandha may affect general mental and brain health by reducing stress.[1][2][3][4] In studies where ashwagandha improved subjective signs and symptoms of stress, factors such as anxiety, cognition, and sleep quality also improved, along with cortisol.[5][6][7] It should be noted that the efficacy of ashwagandha is more pronounced in people reporting both a negative health state and high stress levels.[8][9]
Ashwagandha is best known as an adaptogen, which are compounds that are believed to mitigate physiologic responses and reduce perceived stress. While ashwagandha’s mechanisms of action aren’t well understood in humans, preclinical studies (animal and cell studies) suggest that it may affect regulation of neuronal excitation (with implications for stress resilience) and/or neuroendocrine receptors (with implications for stress-sensitive psychiatric illnesses, such as depression, schizophrenia, and anxiety). [10][11][12][13] If ashwagandha affects neuroendocrine activity by modulating the HPA axis, that may be how it purportedly affects the known neuroendocrine system moderators GABA, DHEA, serum BDNF, cortisol, CRP, testosterone, and serotonin. These neuroendocrine moderators are also tied to stress anxiety, depression, schizophrenia, sleep, cognition, and memory outcomes.
Ashwagandha’s ability to enhance GABAergic (neurotransmitter) activity, as shown in preclinical studies, may be responsible for its apparent anxiolytic effects.[14][15][16][17][18][19][20] [21][13] Effectiveness for sleep has been mirrored in some human studies, where a significant increase in sleep quality (among other sleep related parameters such as improvements in sleep latency, efficiency, duration, alertness, and reduced disturbance) occurred when ashwagandha (120–700mg) was taken daily for periods ranging from 1–3 months. [22][23][24][25][26] It should be noted, however, that prior studies using higher doses of ashwagandha extract (750–2,000 mg, alone or combined with other herbs) did not result in further significant improvements in sleep.[27][28][29]