Ashwagandha is not established as a cause of nighttime wakefulness, but rare reports of thyroid overactivity make a thyroid-mediated explanation biologically plausible in some people.
Try this for 60 seconds tonight
If you are awake and physiologically alert, slow your breathing to about 5–6 comfortable breaths per minute for one minute: inhale gently for roughly 5 seconds, then exhale for roughly 5 seconds. Keep the breath quiet rather than deep or forceful.
The goal is not to “switch off” thyroid activity in 60 seconds. It is simply to reduce unnecessary autonomic arousal while you assess whether your body is settling.
Why the thyroid connection is plausible—but not proven
Ashwagandha (Withania somnifera) is commonly studied for stress, anxiety, and sleep, and controlled trials generally report improvements rather than worsening of sleep. A systematic review of randomized trials found a small overall benefit for sleep, while another review found improvements in several insomnia measures but not consistently in wake-after-sleep-onset. (PubMed)
That makes the idea of “ashwagandha causes nocturnal wakefulness” too broad.
The interesting part is the thyroid axis.
Thyroid hormones → metabolic signaling → effects on many tissues
Thyroxine (T4) and triiodothyronine (T3) influence metabolic activity, thermogenesis, cardiovascular function, and nervous-system activity. Excess thyroid hormone can therefore produce a state that feels quite different from ordinary sleepiness: increased heart rate, heat intolerance, sweating, tremulousness, anxiety, or difficulty sleeping.
There is some human evidence that ashwagandha can affect thyroid measurements. In a small randomized trial involving people with subclinical hypothyroidism, 600 mg/day of extract for eight weeks changed TSH, T3, and T4 compared with placebo. (PubMed)
More recently, a 2026 systematic review and meta-analysis of randomized trials found no significant overall effect on TSH or T3, while T4 increased modestly. The authors also emphasized heterogeneity and limited data for some hormonal outcomes. (PubMed)
So the evidence does not support a simple rule that ashwagandha stimulates the thyroid in everyone.
The rare but important signal
There are published case reports of thyrotoxicosis occurring after ashwagandha use.
One report described a previously healthy woman who developed laboratory-confirmed thyrotoxicosis after increasing her ashwagandha intake; symptoms and laboratory values normalized after discontinuation. (PubMed)
Another report described a patient who developed thyrotoxicosis with supraventricular tachycardia while using ashwagandha, with improvement after stopping the supplement. (PubMed)
A 2024 case report described painless thyroiditis following ashwagandha use, again with improvement after discontinuation. (PubMed)
These reports are important, but case reports cannot establish how frequently this happens or prove that thyroid stimulation explains ordinary nighttime awakenings.
What is well-established
- Ashwagandha has been investigated in randomized trials for sleep and stress.
- Several trials report improved subjective or measured sleep outcomes rather than increased wakefulness. (PubMed)
- Thyroid-related adverse effects have been reported, including rare cases of thyrotoxicosis. (PubMed)
What is plausible
If a particular person’s thyroid function is altered by a supplement, increased physiological activation could potentially contribute to difficulty falling asleep or staying asleep.
That is a reasonable mechanism, but it should not automatically be assumed whenever someone wakes during the night.
What remains uncertain
We do not have good evidence showing that ordinary doses of ashwagandha commonly cause nighttime wakefulness through thyroid stimulation.
The available studies also use different extracts, doses, treatment durations, and participant populations. That makes it difficult to generalize findings from one preparation to another.
Common mistakes
1. Assuming “natural” means hormonally inactive. Ashwagandha contains biologically active compounds and can affect physiological systems.
2. Increasing the dose because the first dose did not seem effective. More is not necessarily better, particularly when the product’s standardized withanolide content differs between preparations.
3. Blaming every nighttime awakening on thyroid hormones. Sleep fragmentation can result from temperature, alcohol, caffeine, stress, medications, sleep apnea, environmental disturbance, circadian timing, and many other factors.
A simple evening approach
If you suspect your supplement is changing your sleep, avoid experimenting with multiple variables at once.
For several nights:
- Keep caffeine and alcohol timing consistent.
- Take note of when the supplement is taken and when awakenings occur.
- If the problem repeatedly began after starting or increasing ashwagandha, discuss the pattern with a clinician rather than automatically increasing or adding another supplement.
- If symptoms suggest thyroid overactivity—particularly persistent palpitations, unusual heat intolerance, tremor, unexplained weight loss, or marked anxiety—medical evaluation is more appropriate than trying to counteract the effect with another sleep supplement.
What this doesn’t mean
It does not mean that ashwagandha is generally bad for sleep.
In fact, controlled studies have found improved sleep quality in several populations, and recent clinical research continues to investigate its potential sleep benefits. (PubMed)
It also does not mean that waking at 2 or 3 AM proves your thyroid is overactive.
The more accurate interpretation is narrower: ashwagandha appears capable of influencing endocrine function in some circumstances, rare thyroid-related adverse events have been documented, and this provides a plausible—but unproven—explanation for sleep disruption in a susceptible individual.
Bottom line
The “thyroid stimulation paradox” is a useful hypothesis, not an established explanation for ashwagandha-induced nocturnal wakefulness. Most controlled sleep research points toward neutral or beneficial sleep effects, while a small body of evidence—including case reports—shows that thyroid-related reactions can occur. If nighttime wakefulness consistently appeared after starting or increasing ashwagandha, the timing deserves attention rather than being dismissed or automatically attributed to insomnia.