Does milk thistle help with sleep? What the research does and doesn't show

No published trial has tested milk thistle, silymarin or silibinin for sleep, in either direction. It hasn't been studied as something that helps you fall or stay asleep, and insomnia isn't listed among the side effects reported in the human safety research reviewed here either.

What the evidence doesn't support

It doesn't support milk thistle as a sleep aid, a treatment for insomnia, or something that helps you fall asleep faster or sleep more deeply. No trial has measured milk thistle's effect on sleep in any of those senses. It also isn't documented as a cause of insomnia in the safety literature reviewed here, though that literature wasn't built to test for sleep effects specifically. Nothing here describes a specific product's dose, and nothing here is a claim about any product.

What the trials found

Nothing directly on sleep. A 2019 safety review of silymarin, covering trials at doses up to 2,100 mg/day for 24 weeks, lists gastrointestinal upset (nausea, diarrhea), headache and skin reactions as the main reported side effects in human participants. Sleep disturbance, insomnia and drowsiness aren't named among them. That absence is worth reading carefully: the trials behind that review were designed to track liver, kidney and metabolic outcomes, not sleep, so an effect on sleep — good or bad — could simply have gone unmeasured rather than not existed. We found no separate trial that measured sleep quality, sleep onset, or insomnia symptoms with milk thistle as the intervention.

Milk thistle tea, specifically, delivers an even smaller and less consistent dose of silymarin than the standardized extracts used in the trials above — silymarin dissolves poorly in water, so a cup of tea is a different exposure entirely from the capsules and tablets tested in the research cited on this site. None of the findings referenced elsewhere on milk thistle transfer directly to tea.

Questions people ask

Does milk thistle help you sleep?

No trial has tested this. There's no published research measuring milk thistle's effect on falling asleep, staying asleep, or sleep quality.

Can milk thistle cause insomnia?

Insomnia isn't listed among the side effects in the human safety research reviewed here, but those trials weren't designed to screen for sleep effects specifically, so this is an absence in the record rather than a direct test.

Is milk thistle tea a sleep tea?

No. Milk thistle isn't studied or marketed for sleep, and tea delivers a much smaller, unstandardized dose of silymarin than any of the research reviewed here used.

When to talk to a doctor

Anyone with ongoing sleep problems, or a diagnosed sleep disorder, should talk to a doctor; milk thistle is not a treatment for insomnia or any other sleep condition, and nothing in the research above tested it as one. If you take a prescription sleep medication or any other medication, ask a doctor before adding milk thistle — see milk thistle and medications: what to check.

Related reading: milk thistle tea, milk thistle side effects, and what is milk thistle.