Limited evidenceSleep & relaxation

Honokiol

A biphenyl compound from magnolia bark with a clear sedative mechanism in animals. No human trial has tested isolated honokiol for sleep or anxiety; the only clinical data come from whole magnolia bark blends.

Evidence last reviewed: August 2026

What the science says

Promotes non-REM sleep in animals Limited evidence
A controlled mouse study showed that honokiol increases non-rapid-eye-movement sleep and shortens sleep latency, and that the effect is blocked by flumazenil, indicating action at the benzodiazepine site of the GABA-A receptor. This is a well-characterised mechanism but was demonstrated only in rodents.
Stress and cortisol in humans Limited evidence
A small pilot double-blind placebo-controlled trial in healthy women found modest reductions in self-reported stress with a proprietary magnolia and phellodendron bark extract. The product was a multi-ingredient blend rather than isolated honokiol, so the contribution of honokiol itself cannot be separated.
Anxiety reduction Limited evidence
No randomised trial has measured validated anxiety scales with purified honokiol in people. The anxiolytic reputation is extrapolated from receptor binding data and rodent behavioural models.

Dosage & safety

Studied doseNo established human dose for isolated honokiol. Magnolia bark extracts used in human studies supplied roughly 250–750 mg per day of combined bark extract; supplements standardised to honokiol commonly list 100–250 mg per day as a label dose.

SafetyHuman safety data are limited to short pilot trials of bark blends, where side effects were mild. Because honokiol acts at the benzodiazepine site, do not combine it with alcohol, benzodiazepines, z-drugs or other sedatives, and do not drive after taking it until you know how it affects you. Avoid in pregnancy and breastfeeding; caution with anticoagulants given reported antiplatelet activity.

Scientific references

Honokiol promotes non-rapid eye movement sleep via the benzodiazepine site of the GABA(A) receptor in mice
Qu WM, Yue XF, Sun Y — Br J Pharmacol, 2012
Effect of a proprietary Magnolia and Phellodendron extract on stress levels in healthy women: a pilot, double-blind, placebo-controlled clinical trial
Kalman DS, Feldman S, Feldman R — Nutr J, 2008

Where to buy

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