Why Ashwagandha Makes You Tired, Lethargic, or Emotionally Flat — and What to Do

If you've scrolled through r/Supplements at 2 a.m. wondering why the herb that was supposed to mellow you out has left you flat, foggy, and oddly numb, you're not imagining it. The threads repeat the same story: "Started ashwagandha for anxiety, three weeks in I feel like a zombie", "It killed my stress but also killed my motivation", "ashwagandha made me feel depressed and flat — anyone else?"

You bought it for the calm. Somewhere along the way the calm turned into a heaviness you can't shake.

Here's the thing I want you to hear first: this isn't in your head, and it isn't a sign the herb is "bad." Ashwagandha makes some people tired, lethargic, or emotionally blunted because of how its active compounds actually work in the brain — by interacting with GABA, by lowering cortisol, and (more speculatively) by shifting stress-hormone and neurotransmitter signaling in ways that mute both anxiety and drive. When those effects overshoot, you end up calm in a way that doesn't feel like you anymore.

This is a real, documented, dose-and-extract-dependent response — not the one-line "may cause drowsiness" you'll find buried in a supplement facts box.

If you're new to ashwagandha and want the full benefits-and-mechanism picture first, start with our Ashwagandha Benefits: The Complete Science Guide. This piece is for when the benefits come with a cost you didn't expect.

In the next few minutes I'll walk through why ashwagandha makes you tired, whether what you're feeling is in the "normal, adjust your dose" zone or the "stop and reassess" zone, and the practical levers — dose, timing, extract type, cycling — that fix it for most people.

The Quick Answer — Why Ashwagandha Makes You Tired

Ashwagandha makes some people tired because its active compounds (a family of steroidal lactones called withanolides) interact with your brain's GABA system and lower your body's output of cortisol, the main stress hormone. For most users, that's exactly the point — less stress, easier sleep, a softer edge. But when the dose is too high, the extract is too potent, or you take it at the wrong time of day, that same calming effect tips over into drowsiness, brain fog, and a flattened emotional tone.

The short version: the calm you wanted became the sedation you didn't.

Here's a quick lookup table for the questions people ask most:

Now let's get into the why, because understanding the mechanism is what tells you which lever to pull.

Why It Happens — The Mechanisms Behind Ashwagandha Fatigue

Most big health sites stop at "it lowers stress." That's true but it skips the part that explains why your experience can be so different from your friend's. Three overlapping mechanisms are doing the work, and which one dominates for you depends on your dose, your extract, your timing, and your own neurochemistry.

Mechanism 1 — GABA Mimicry (The "Sedation" Pathway)

GABA (gamma-aminobutyric acid) is your brain's principal inhibitory neurotransmitter — the chemical that tells neurons to quiet down. Drugs that boost GABA signaling (benzodiazepines, alcohol, z-drugs, many sleep aids) all share a familiar side-effect profile: sedation, grogginess, and a next-day "hangover."

Ashwagandha sits, biochemically, in the same neighborhood. An aqueous extract of Withania somnifera has been shown to directly activate GABA-A receptors in mammalian cortical neurons (Candelario et al., 2015). Separately, in vitro work has shown that a hydroalcoholic ashwagandha extract upregulates the expression of GABA and histamine receptors in cell and rodent models, plausibly supporting its sleep-promoting effect (Murthy et al., 2022, PMC9007714).

A nuance worth being honest about: it's not necessarily withaferin A or withanolide A (the two most-studied withanolides) doing the GABA work directly. The same 2015 study that confirmed whole-extract GABA-A activity reported that those two purified compounds did not directly activate GABA-A receptors — suggesting other withanolide derivatives in the plant are responsible (Candelario et al., 2015). The point for you is the same regardless: the net effect of the whole extract is a GABA-leaning, calming signal, and that signal lingers.

That lingering is what produces the ashwagandha GABA effect, tired the next day that shows up in so many user reports. If you dose at 10 p.m. and the calming signal is still working at 7 a.m., you wake up into a brain that's still being told to be quiet.

Here's roughly what a day on ashwagandha looks like at the neurotransmitter level — a mechanistic sketch of why the next-morning grogginess happens:

A caveat on those time values: ashwagandha's full pharmacokinetic profile in humans isn't well mapped, so treat this as a mechanistic sketch, not a minute-by-minute graph. The shape of it — onset, sustained calm, and a next-morning tail — matches what users describe.

Mechanism 2 — Cortisol and HPA-Axis Suppression ("Cortisol Overshoot")

Your second pathway out of "calm" and into "tired" runs through cortisol.

Ashwagandha's best-evidenced benefit is stress reduction, and the mechanism that delivers it is modulation of the HPA axis (hypothalamic-pituitary-adrenal axis) — the system that governs your cortisol response. A 2025 systematic review and meta-analysis found that ashwagandha supplementation produced a statistically significant reduction in cortisol levels, even though its effect on subjective perceived-stress scores did not reach significance (Albalawi, 2025). A separate review of cortisol-specific trials reports plasma cortisol dropping on the order of 11–33% in stressed but healthy adults (Della Porta et al., 2023).

For most people, that's the entire reason they bought the bottle. Less circulating cortisol = less wired, less on edge, better sleep.

But here's the catch: cortisol isn't just a "stress" hormone. It's also what gets you out of bed in the morning, what holds your blood pressure up when you stand, and what gives you the biochemical push behind motivation. It has a normal daily curve — a healthy morning spike (the cortisol awakening response) and a gradual evening decline. If you flatten that curve too hard, for too long, with too high a dose, you can tip from "calm" into ashwagandha cortisol-too-low fatigue: heaviness on waking, low blood pressure, brain fog, and that "zombie" feeling that no amount of coffee fixes cleanly.

Is that over-suppression common? No. But it isn't theoretical, either. A 2022 case report documented a patient who developed adrenal hypofunction after about ten weeks of ashwagandha supplementation — and whose adrenal function recovered after a two-week break (Fry et al., 2022). One case isn't an epidemic, but it lines up with the mechanistic story and with the low-grade "I feel flattened" reports you'll see in forum threads.

The takeaway for you: if your fatigue comes with dizziness on standing, unexplained weight loss, or a complete inability to get going in the morning even after good sleep, don't keep pushing the dose — that's the profile to stop and check in with a clinician about.

Mechanism 3 — Dopamine, Serotonin, and Emotional Blunting (The "Flatness" Pathway)

This is the mechanism that gets the least airtime and causes the most confusion, because it shows up as a feeling rather than a measurable lab value. People describe it as emotional numbness, anhedonia, flat affect, "robot mode." Anxiety is gone — but so is excitement, drive, sometimes even the texture of pleasure.

The honest scientific status of this pathway: it's a plausible mechanism with limited human data. What we have is mostly preclinical. Reviews of Withania somnifera's pharmacology note that its withanolides modulate not only GABA but also serotonergic and dopaminergic signaling in animal models, alongside effects on stress-hormone pathways (Speers et al., 2021, PMC8762185; see also Jamnekar et al., 2025, PMC12680924). In an animal model, an ashwagandha formulation mitigated sleep-deprivation-induced drops in serum serotonin and dopamine (Er et al., 2025).

So why would something with stress-buffering activity in animals make a human feel emotionally flat? Two things to keep in mind:

1. Animal models aren't humans, and a rodent neurotransmitter result is a long way from "how you feel at your job on a Tuesday."
2. The likely mechanism behind the flatness some users report is an overshoot of the same stress-buffering effect — blunt the stress signal hard enough, for long enough, and you may blunt the signal that gives emotional experiences their contrast and color. That's a hypothesis, not a proven fact.

What I can say with confidence: when users report ashwagandha emotional numbness / anhedonia, the effect is almost always dose-dependent and reversible — it shows up at higher doses, builds over weeks of daily use, and lifts within days to weeks of stopping or lowering the dose. There is no credible evidence that ashwagandha causes permanent emotional blunting or lasting anhedonia. If that's the worry keeping you up (ironically), you can set it down.

Is Emotional Numbness and Lethargy on Ashwagandha Normal?

"Normal" is a loaded word. Let me reframe it.

What's common on ashwagandha: mild drowsiness, deeper sleep, a slight softening of reactivity in the first week or two. These are the expected effects of a compound that engages GABA and lowers cortisol — for many people they're the whole point.

What's common but under-discussed: the subset of users for whom ashwagandha makes them lethargic and unmotivated, not just calm. The r/Nootropics and r/Supplements archives are full of variations on "killed my anxiety but also my motivation," "feel emotionally blunted after about three weeks," "like there's a ceiling on how good or bad I can feel." The NIH Office of Dietary Supplements notes that ashwagandha's reported side effects include drowsiness and gastrointestinal symptoms and that it appears well-tolerated for up to about three months, while long-term safety data remain limited (NIH ODS Ashwagandha Fact Sheet). NCCIH similarly lists drowsiness as a known side effect and considers ashwagandha possibly safe for short-term use (up to around three months) (NCCIH).

So "normal" in the sense of recognized and documented? Yes. "Normal" in the sense of something you should just put up with? No. Fatigue that erodes your ability to do your life is a signal, not a rite of passage.

Here's a rough triage table for thinking about where you fall:

If you're in the left column, you're in adjustment territory. Middle column? Time to pull the levers in the next sections — and quite possibly take a break. Right column? Stop, and talk to a healthcare professional.

KSM-66 vs Sensoril — Which Extract Makes You Less Tired?

If you've only ever bought "ashwagandha" without looking at the extract name on the back of the bottle, this is the single biggest variable you've been missing. Not all ashwagandha is the same stuff, and the extract choice goes a long way toward explaining why your experience differs from someone else's.

The two names you'll see most:

• KSM-66 — a full-spectrum, root-only extract, standardized to ≥5% withanolides per the manufacturer's specification. It's made using a milk-pretreatment process and has one of the larger bodies of clinical-trial support for stress and cortisol outcomes (Chandrasekhar et al., 2012, PMC3573577).
• Sensoril (also sold as NooGhanda) — a root-and-leaf extract standardized to a higher withanolide content, typically around 8–10%. It tends to be marketed for sleep and intense anxiety and is used at a lower dose (often 125–250 mg/day) because it's more concentrated.

The pattern you'll see in forum reports and that lines up with the mechanism: the higher the withanolide load relative to your tolerance, the more likely you are to get the sedation/flatness profile. That makes Sensoril — stronger per milligram — more often the culprit in the "ashwagandha KSM-66 vs Sensoril fatigue" and "I felt numb" threads. KSM-66, being milder per milligram and root-only, is more often described as an "energized calm."

Let me be straight with you about the limits here: direct head-to-head RCTs comparing KSM-66 vs Sensoril specifically for fatigue or emotional blunting do not exist. The pattern is forum-dominant and mechanistically plausible — higher withanolide % means a stronger GABAergic / cortisol-suppressing signal, which in susceptible people means more sedation — but it is not proven by a controlled trial. Treat the table as a well-grounded starting hypothesis, not a guarantee.

The practical advice that falls out of it: if fatigue or numbness is your problem and you're on a Sensoril-type extract, try switching to KSM-66 before quitting ashwagandha entirely. Plenty of people who "can't tolerate ashwagandha" turn out to specifically not tolerate high-withanolide ashwagandha.

And if the daytime fatigue is too much but you still want the sleep and anxiety benefit, magnesium pairs well with ashwagandha — here's how to stack them safely. Layering magnesium in often lets you lower the ashwagandha dose while keeping the calming effect.

Timing — Morning vs Night to Avoid Fatigue

The other lever people overlook: when you take it. Because the GABA and cortisol effects have a multi-hour tail, timing can be the difference between "calm and clear" and "foggy until noon."

The general principle:

• If you're taking KSM-66 for daytime stress, morning or early afternoon lines the calm up with the part of the day you actually need it, and lets the tail fade before bed.
• If you're taking Sensoril (or any higher-withanolide extract) for sleep, 30–60 minutes before bed is the right window — you want the sedation to land on your pillow, not on your morning commute.
• If you're already getting next-day grogginess, the single most common fix is moving the dose earlier, not lowering it. A dose taken at 10 p.m. with a 12+ hour tail will still be working on you at 10 a.m.

Same honesty as with the extract comparison: there's no big RCT that pinned down "best time to take ashwagandha, morning vs night, to avoid fatigue" as a primary endpoint. The guidance above is mechanistically reasoned from how the GABA and cortisol effects persist over time, and it lines up with what users report. It's a good first experiment, not a prescription.

How Long Until Side Effects Fade — and Should You Cycle?

Two questions land here: if I stop, when do I feel like me again? and should I have been taking breaks all along?

Time to recover after stopping. The GABA-mediated drowsiness and brain fog usually clear within a few days of stopping — that signal is tied to active withanolide levels, which fall relatively quickly. The HPA-axis / cortisol recalibration is slower, on the order of one to two weeks in most reports. The 2022 case report of ashwagandha-associated adrenal hypofunction found full recovery after a two-week break (Fry et al., 2022) — a useful data point for the "how long is too long to still feel off" question.

Cycling. There is no official clinical guideline for cycling ashwagandha — the trials that established its effects mostly ran 8–12 weeks of daily use without a structured break. The common practice (in both clinician-oriented supplement communities and in forum discussions) is something like 8–12 weeks on, 2–4 weeks off. The reasoning isn't that daily use is proven harmful; it's that we don't have strong long-term safety data, and the anecdotal pattern of tolerance-shift, emotional flattening, and next-day fatigue clusters around continuous, uninterrupted, daily, high-dose use. If you're someone who hits the flatness/lethargy profile, cycling isn't optional housekeeping — it's likely the fix.

Withdrawal and rebound. One more thing to be straight about: ashwagandha is not classically addictive, but abrupt discontinuation after long-term use can produce withdrawal-like symptoms. A 2025 case report in Cureus documented a 20-year-old male who developed tachycardia, insomnia, and anxiety after stopping ashwagandha abruptly (Holzman et al., 2025; PMC mirror). It's a single case, not evidence that everyone who stops gets withdrawal — but it's a reasonable argument for tapering down rather than cold-turkey if you've been taking it daily for months.

When to Stop — Red Flags

Most of what we've covered so far is in the "adjust and keep going" zone. This section is about the times you should stop.

Stop and talk to a healthcare professional if you experience any of the following while taking ashwagandha:

• Persistent low mood, depressive symptoms, or any thoughts of self-harm. Calm-with-flatness is one thing; a real depressive shift is another and deserves real care.
• Thyroid symptoms — palpitations, heat intolerance, unexpected weight changes, tremor, or (going the other direction) cold intolerance and deep fatigue. Ashwagandha may influence thyroid hormone levels, so the NIH ODS fact sheet flags thyroid disorders and thyroid medication as areas for caution (NIH ODS).
• Signs of adrenal insufficiency — dizziness or near-fainting when standing, low blood pressure, significant unexplained weight loss, or profound morning fatigue that doesn't resolve. These line up with the symptoms documented in the published case report of ashwagandha-associated adrenal hypofunction (Fry et al., 2022).
• Palpitations, chest pain, or anything that feels cardiovascular.
• Signs of liver injury — yellowing of skin or eyes, dark urine, upper-right abdominal pain, severe fatigue. Hepatic adverse events associated with ashwagandha have been reported in the literature — a 2025 review noted that at least six cases of ashwagandha-associated liver injury have been documented, all reversible (Sprengel et al., 2025, PMC11800443).

Who should check with a clinician before starting (or continuing) ashwagandha at all: anyone who is pregnant or breastfeeding, anyone with a thyroid disorder or on thyroid medication, anyone with an autoimmune condition, and anyone taking sedating medications, anti-anxiety medication, or other GABAergic drugs. Several of these interactions are exactly what you'd predict from the mechanisms above — stacking GABAergic effects or perturbing an already-regulated endocrine axis is where trouble shows up.

If you decide ashwagandha isn't tolerable for you, magnesium glycinate is a gentler, well-tolerated option for sleep and anxiety — see our comparison of magnesium glycinate, threonate, and citrate. For many people who get the flatness/fatigue response, magnesium alone gives a softer, more daytime-friendly calm without the emotional ceiling.

Quick FAQ

Why does ashwagandha make me tired the next day? Because its withanolides interact with your GABA system and lower cortisol — and both signals have a multi-hour tail. A dose taken at night can still be quietly telling your brain "be calm" when your alarm goes off. Moving the dose earlier, lowering it, or switching to a milder extract (KSM-66) usually fixes it.

Is emotional numbness from ashwagandha permanent? No. It's dose-dependent and reversible. Most people recover within days to weeks of stopping or lowering the dose. There's no credible evidence that ashwagandha causes lasting anhedonia.

Should I take ashwagandha in the morning or at night? It depends on your extract and your goal. KSM-66 for daytime stress is best in the morning or early afternoon. A higher-withanolide extract like Sensoril for sleep is best 30–60 minutes before bed. If next-day grogginess is your issue, the simplest fix is moving the dose earlier rather than lower.

Can cortisol get too low on ashwagandha? Rare, but possible with chronic high-dose use — and documented in at least one published case report of reversible adrenal hypofunction. Symptoms to watch for: fatigue, low blood pressure, dizziness on standing, and profound difficulty waking.

Is KSM-66 or Sensoril better for avoiding fatigue? Anecdotally and mechanistically, KSM-66 (root-only, ~5% withanolides) is less associated with drowsiness and emotional flatness. Sensoril (root + leaf, ~8–10% withanolides) is more potent per milligram and tends to be more sedating. Head-to-head RCTs don't exist, so treat this as a well-grounded hypothesis rather than proven fact.

How long do ashwagandha side effects last after stopping? Usually a few days to two weeks. GABA-related drowsiness clears fast; full HPA-axis/cortisol recalibration can take a week or two. If symptoms persist beyond that, see a clinician.

The Bottom Line

Ashwagandha fatigue, lethargy, and emotional flatness aren't a sign you're "doing it wrong" or that the herb is broken. They're the predictable downstream effects of three real mechanisms — GABA engagement, cortisol/HPA-axis suppression, and (more speculatively) shifts in monoamine signaling — overshooting in your particular neurochemistry, at your particular dose, with your particular extract, at your particular time of day.

That's actually good news, because it means you have levers. Here's the order I'd work through:

1. Cut your dose in half. The single most common fix, and the one people skip most often.
2. If you're on Sensoril or a high-withanolide extract, switch to KSM-66. Many "ashwagandha doesn't work for me" stories are really "Sensoril doesn't work for me" stories.
3. Move the timing. Earlier in the day if you're getting brain fog; before bed only if sleep (not daytime stress) is your goal.
4. Take a 2–4 week break. Especially if you've been daily-dosing for months. Reassess how you feel off it.
5. If the flatness, lethargy, or depressive symptoms don't lift — or any red-flag symptoms show up — stop and talk to a clinician. Not every supplement is for every body, and that's fine.

If ashwagandha left you flat when you expected calm, you're not alone — it's one of the most under-discussed effects out there. Drop a comment with what you felt and what you changed. For the complete picture of what ashwagandha does right when it does work for you, see our Ashwagandha Benefits: The Complete Science Guide. And if you want to keep the sleep and anxiety benefits while sidestepping the fatigue, our Ashwagandha + Magnesium Sleep & Anxiety Stack Guide breaks down how to layer them safely.

This article is for informational purposes only and is not a substitute for professional medical advice. Ashwagandha can interact with medications and may not be appropriate for people with certain medical conditions. Talk to a healthcare professional before starting or stopping any supplement — especially if you're pregnant, nursing, managing a thyroid or autoimmune condition, or taking sedating or anti-anxiety medication.

References

1. Candelario M, Cuellar E, Reyes-Ruiz JM, Darabedian N, Feimeng Z, Miledi R, Russo-Neustadt A, Limon A. Direct evidence for GABAergic activity of Withania somnifera on mammalian ionotropic GABAA and GABAρ receptors. J Ethnopharmacol. 2015;171:264-272. PMID: 26068424. https://pubmed.ncbi.nlm.nih.gov/26068424/
2. Murthy SV, Fathima SN, Mote R. Hydroalcoholic extract of ashwagandha improves sleep by modulating GABA/histamine receptors and EEG slow-wave pattern in in vitro–in vivo experimental models. Prev Nutr Food Sci. 2022;27(1):108. PMC9007714. https://pmc.ncbi.nlm.nih.gov/articles/PMC9007714/
3. Albalawi AA. Dual impact of ashwagandha: significant cortisol reduction but no effects on perceived stress — a systematic review and meta-analysis. Nutr Health. 2025;31(4):1395-1408. PMID: 40746175. https://pubmed.ncbi.nlm.nih.gov/40746175/
4. Della Porta M, Maier JA, Cazzola R. Effects of Withania somnifera on cortisol levels in stressed human subjects: a systematic review. Nutrients. 2023;15(24):5015. https://www.mdpi.com/2072-6643/15/24/5015
5. Fry CH, Fluck D, Han TS. Adrenal hypofunction associated with ashwagandha (Withania somnifera) supplementation: a case report. Toxicol Environ Health Sci. 2022. https://link.springer.com/article/10.1007/s13530-022-00122-z
6. Speers AB, Cabey KA, Soumyanath A, Wright KM. Effects of Withania somnifera (ashwagandha) on stress and the stress-related neuropsychiatric disorders anxiety, depression, and insomnia. Curr Neuropharmacol. 2021;19(9):1468-1495. PMC8762185. https://pmc.ncbi.nlm.nih.gov/articles/PMC8762185/
7. Jamnekar PP, Dehankar TJ, Bedre RV, Dharan BG, Agravat H, Agravat B. Ashwagandha as an adaptogenic herb: a comprehensive review of immunological and neurological effects. Cureus. 2025;17(11):e96183. PMC12680924. https://pmc.ncbi.nlm.nih.gov/articles/PMC12680924/
8. Er B, Ozmen B, Sahin E, Orhan C, Sahin N, Morde AA, Padigaru M, Sahin K. A novel ashwagandha (Withania somnifera) formulation mitigates sleep deprivation-induced cognitive impairment and oxidative stress in a rat model. Biomolecules. 2025;15(5):710. https://www.mdpi.com/2218-273X/15/5/710
9. Chandrasekhar K, Kapoor J, Anishetty S. A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root in reducing stress and anxiety in adults. Indian J Psychol Med. 2012;34(3):255-262. PMC3573577. https://pmc.ncbi.nlm.nih.gov/articles/PMC3573577/
10. Holzman A, Brown AE, Kelley J, Rappaport D, Martini WA. Unmasking potential withdrawal effects of ashwagandha: a case report and review. Cureus. 2025;17(5):e83577. https://www.cureus.com/articles/367499-unmasking-potential-withdrawal-effects-of-ashwagandha-a-case-report-and-review (PMC mirror: https://pmc.ncbi.nlm.nih.gov/articles/PMC12139691/)
11. National Institutes of Health, Office of Dietary Supplements. Ashwagandha: fact sheet for health professionals. https://ods.od.nih.gov/factsheets/Ashwagandha-HealthProfessional/
12. National Center for Complementary and Integrative Health (NCCIH). Ashwagandha: usefulness and safety. https://www.nccih.nih.gov/health/ashwagandha
13. Sprengel M, Laskowski R, Jost Z. Withania somnifera (ashwagandha) supplementation: a review of its mechanisms, health benefits, and role in sports performance. Nutr Metab. 2025;22:9. PMC11800443. https://pmc.ncbi.nlm.nih.gov/articles/PMC11800443/