Ashwagandha (Withania somnifera)

Ashwagandha is the root of Withania somnifera, a nightshade used for centuries in Ayurveda as a rasayana (rejuvenating tonic). Its active compounds are steroidal lactones called withanolides; supplements are standardised to a percentage of these (e.g. KSM-66 at ~5%).

Adaptogens are meant to blunt the body’s stress response and help it return to balance. Ashwagandha’s withanolides appear to calm the HPA (hypothalamic-pituitary-adrenal) axis — lowering elevated cortisol — and have GABA-mimetic, mildly sedative activity, which is why the same herb both eases daytime stress and supports sleep. It also shows antioxidant and mild anti-inflammatory effects.

In a randomised, double-blind trial, 300 mg KSM-66 twice daily for 60 days reduced perceived-stress scores and cut serum cortisol by 27.9% versus 7.9% on placebo (P=0.002).¹ Multiple later trials and meta-analyses agree it modestly reduces stress and anxiety, and a 2021 meta-analysis found modest improvements in sleep in some trials — most clearly at ≥600 mg/day for ≥8 weeks.² That does not make it a dependable sleep aid: the effect is small and inconsistent, and a minority of people report the opposite — feeling wired or restless, or sleeping worse. The evidence is genuine but mostly short (6–12 weeks), on small groups, and often industry-funded.

300–600 mg/day of a standardised extract, once or twice daily. Many take it in the evening when sleep is the goal — but a minority find it activating rather than calming, and anyone who feels wired or sleeps worse on it should move the dose to the morning (or stop). Start low, and see how you respond before taking it at night. Allow 6–12 weeks. Effects are gradual, not acute.

Generally well tolerated — mild drowsiness or digestive upset are the usual complaints, with rare reports of liver injury. Avoid in pregnancy (traditionally abortifacient). It can raise thyroid hormone (caution in hyperthyroidism or on thyroid medication), may lower blood sugar and blood pressure, and adds to sedatives. Note a paradoxical reaction in some sensitive people — instead of calming them it can feel over-stimulating or restless and worsen sleep; if that happens, take it earlier in the day or stop. Best for adults under chronic stress or with stress-driven poor sleep — not a treatment for clinical anxiety or depression.