Passionflower for Relaxation: What the Clinical Research Suggests

Published June 2026 · 7 min read

Among botanicals used for evening calm, passionflower may have the widest gap between its long history and its current scientific understanding. It's been used for centuries across two continents, the preliminary clinical data is genuinely encouraging, and yet by any rigorous standard the research is still early. This article covers the traditional roots, proposed mechanism, key human studies, the NCCIH position, and honest dose context.

What Passionflower Is

Passiflora incarnata—commonly called passionflower or maypop—is a climbing vine native to the southeastern United States, Central America, and South America. Spanish missionaries in the 16th century named it for the Passion of Christ after encountering its intricate flowers. The parts used in herbal preparations are the above-ground portions: leaves, stems, and flowers. There are over 500 species in the Passiflora genus, but P. incarnata is the species studied in virtually all clinical trials and the one a supplement label should refer to.

Traditional Use: From the Americas to Europe

Indigenous peoples across the Americas used passionflower long before European contact. Native American tribes, including the Cherokee, used it as a calming botanical. The Aztecs reportedly used it as a sedative and pain-relieving agent. European colonizers brought it across the Atlantic, and by the 19th century it was a fixture in European herbal medicine for nervousness, restlessness, and sleep difficulty—included in the British Herbal Pharmacopoeia and recognized by the German Commission E for nervous restlessness.

Today, the European Medicines Agency lists passionflower as a "traditional herbal medicinal product" for mild mental stress and sleep support. That designation is based on historical use, not confirmed modern clinical efficacy—an important distinction.

The Proposed Mechanism: GABAergic Activity

Researchers have proposed that passionflower's calming effects may involve the GABA (gamma-aminobutyric acid) system—the brain's primary inhibitory neurotransmitter, the same system that reishi mushroom is thought to interact with, the chemical messenger that tells neurons to slow down. Laboratory studies have identified bioactive compounds in P. incarnata, including flavonoids like chrysin and apigenin, that appear to interact with GABA-A receptors in ways similar—though much milder—to pharmaceutical anxiolytics.

However, this mechanism has been demonstrated primarily in preclinical models. Whether the same GABAergic pathway operates in humans at supplement doses hasn't been definitively established. It's a plausible hypothesis that aligns with traditional use, but the mechanistic picture in humans isn't yet complete.

The Human Clinical Studies

Passionflower has something many traditional botanicals lack: controlled human trials. The evidence base is small, but real.

Akhondzadeh et al. (2001) — Comparison Trial

What they did: A randomized, double-blind trial comparing passionflower extract (45 drops/day) against oxazepam over 4 weeks in 36 participants.

What they found: Both groups showed similar improvements on the Hamilton Anxiety Rating Scale. The passionflower group reported fewer issues with daytime drowsiness and job performance impairment, though with slower onset during the first week.

Limitations: Small sample (n=36), single-site, no placebo-only arm. Still, comparable outcomes with better tolerability are noteworthy signals.

Appel et al. (2011) — GABA Modulation and Sleep

What they did: A placebo-controlled crossover trial examining passionflower herbal tea (approximately 2 grams of dried herb per cup) in 41 healthy participants over one-week periods.

What they found: Significant improvements in subjective sleep quality compared to placebo. Notably, objective measures (polysomnography) did not show significant differences—a gap between how people felt and what instruments detected.

Ngan & Conduit (2011) — Sleep Quality in Healthy Adults

What they did: A double-blind, placebo-controlled study where 41 participants consumed passionflower tea (2 grams of P. incarnata) or placebo for seven days, with sleep diaries and polysomnography.

What they found: Statistically significant improvements in overall sleep quality on diary measures. Polysomnography showed trends but did not reach significance—consistent with Appel's findings.

The collective picture: Two independent placebo-controlled studies, both finding subjective sleep quality improvements. The consistency is encouraging. The modest effect sizes and subjective-objective disconnect are honest limitations.

What the NCCIH Says

The NCCIH, part of the NIH, maintains a cautious but not dismissive position: research on passionflower for anxiety and sleep is limited, and there isn't enough evidence to draw firm conclusions about effectiveness. At the same time, passionflower is generally considered safe for most people when used short-term (up to two months in clinical studies). "Limited research" means we need more data, not that existing data is wrong.

Dose Transparency: The Honest Conversation

The clinical studies above used doses ranging from approximately 200 mg of concentrated extract (Akhondzadeh) to 2,000 mg of dried herb in tea preparations (Appel, Ngan & Conduit). Most published research falls in the 400–2,000 mg range.

Pilly Labs Reishi Relax Gummies contain 25 mg of passionflower extract per serving. That is below the doses used in standalone studies. We want to be upfront about that.

The rationale: our product is a multi-botanical evening support formula—Reishi mushroom (200 mg), L-theanine (25 mg), lemon balm (25 mg), passionflower (25 mg), and valerian root (25 mg)—designed so that multiple calming ingredients with complementary mechanisms work together. Passionflower is one thread in a broader formula, not a standalone intervention at clinical-trial doses. For a liquid option, our Reishi Calm Drops take a similar multi-ingredient approach in tincture form.

You deserve to know the dose context rather than having it buried behind marketing language. If you want passionflower at clinical-trial doses, a standalone supplement at 400+ mg would be more aligned with the published research.

Safety Considerations

Passionflower has a favorable safety profile at studied doses, but there are considerations worth knowing:

• Drowsiness: Some people experience drowsiness. Start low if you're sensitive to sedating botanicals, and avoid driving or operating machinery until you know how it affects you.
• Surgery: NCCIH recommends discontinuing passionflower at least two weeks before scheduled surgery, as it may interact with anesthesia.
• Pregnancy and breastfeeding: Insufficient safety data. Most sources recommend avoidance.
• Drug interactions: May enhance sedative effects and could interact with sedative medications or anticoagulants. Consult your healthcare provider if you take prescription medications.

How Passionflower Works Alongside Other Calming Ingredients

Different calming ingredients may support relaxation through distinct pathways:

• Passionflower may support GABA receptor activity through flavonoid compounds
• L-theanine promotes alpha brain waves and modulates GABA, serotonin, and dopamine
• Lemon balm may slow GABA breakdown through GABA-transaminase inhibition
• Valerian root has traditional use for sleep support and may also interact with GABA pathways
• Reishi mushroom has centuries of traditional Chinese medicine use as a calming tonic

No published study has tested this exact five-ingredient combination. The rationale is based on individual evidence profiles and complementary proposed mechanisms. A reasonable formulation approach, but not a clinically validated stack.

The Bottom Line

Passionflower is a botanical with deep traditional roots and encouraging—but still limited—clinical evidence. The human studies suggest it may support relaxation and subjective sleep quality, with a mechanism that plausibly involves the GABA system. The NCCIH considers it generally safe short-term while calling for more research.

As part of a thoughtful evening wind-down routine—alongside good sleep hygiene and reasonable expectations—passionflower is a reasonable ingredient to consider. Not a miracle. A traditional botanical with preliminary modern support, best understood as one component in a broader approach to evening calm.

References

Note: These citations reflect ingredient-level research, not finished-product claims. Results from individual studies may not directly apply to specific supplement formulations.

1. Akhondzadeh S, Naghavi HR, Vazirian M, Shayeganpour A, Rashidi H, Khani M. Passionflower in the treatment of generalized anxiety: a pilot double-blind randomized controlled trial with oxazepam. J Clin Pharm Ther. 2001;26(5):363-367.
2. Appel K, Rose T, Fiebich B, Kammler T, Hoffmann C, Weiss G. Modulation of the gamma-aminobutyric acid (GABA) system by Passiflora incarnata L. Phytother Res. 2011;25(6):838-843.
3. Ngan A, Conduit R. A double-blind, placebo-controlled investigation of the effects of Passiflora incarnata (passionflower) herbal tea on subjective sleep quality. Phytother Res. 2011;25(8):1153-1159.
4. Miroddi M, Calapai G, Navarra M, Minciullo PL, Gangemi S. Passiflora incarnata L.: ethnopharmacology, clinical application, safety and evaluation of clinical trials. J Ethnopharmacol. 2013;150(3):791-804.
5. Janda K, Wojtkowska K, Jakubczyk K, Antoniewicz J, Skonieczna-Zydecka K. Passiflora incarnata in neuropsychiatric disorders—a systematic review. Nutrients. 2020;12(12):3894.