Benefits
More deep (non-REM) sleep on an overnight brain-wave recording
In a study that recorded sleep with EEG, 50 mg of the leaf extract taken on its own increased non-REM (deeper) sleep time by 7.6%. It did not shorten the time taken to fall asleep; a separate GABA arm did that, by about 5.3 minutes, and combining the two was no better than either alone. This is one small study, run by an ingredient company, measuring a sleep trace rather than how rested people felt.
Self-rated sleep problems in an open crossover study
In an open (unblinded) randomized crossover study of 160 adults that tested four sleep-support ingredients, 50 mg a day of the leaf extract was among those that eased self-reported sleep problems. Without a placebo group the result cannot be firmly separated from expectation, and the study relied on people's own ratings rather than objective sleep measures.
Activity at a calming brain receptor in laboratory and animal work
In laboratory and mouse experiments, the branded leaf extract bound the benzodiazepine site of the GABA-A receptor, reduced the time mice took to fall asleep and lengthened non-REM sleep, and the sedative antagonist flumazenil blocked the effect. This describes a plausible mechanism from lab and animal studies; it has not been confirmed as a sleep effect measured in people.
Mood-related behavior in animal models only
In mice, a flavonoid extract of the leaves lowered immobility in the forced-swim and tail-suspension tests and raised noradrenaline and dopamine in the hippocampus. These are animal behavior models, not measurements in people. A published review classed this plant as having only preclinical evidence for calming activity, with no human clinical trials of mood or anxiety.
Mechanism of action
Flavonoids hyperoside and isoquercitrin
The leaf extract is standardized to two quercetin glycosides, hyperoside and isoquercitrin. Laboratory and animal studies attribute the plant's reported calming and sleep activity to these flavonoids, but how much of either reaches the brain in people taking the supplement has not been established.
GABA-A benzodiazepine site (laboratory and animal findings)
In binding assays the branded extract showed affinity for the benzodiazepine site on the GABA-A receptor, the same site that sedative medicines act on. In mice, the sleep effect was reversed by flumazenil, which blocks that site. This is a mechanism from cell and animal work, not something measured in human brains.
Traditional calming use and the blood-pressure context
In Chinese herbal tradition the leaf (Luobuma) was used to calm the nerves and for high blood pressure, and reviews note blood-pressure-lowering effects in animal pharmacology studies. This is background and tradition. The cited human research measured sleep, not blood pressure, and traditional use is not the same as a tested benefit.
Clinical trials
Human study recording sleep by EEG, comparing GABA alone, Apocynum venetum leaf extract alone at 50 mg, and the two combined; run by an ingredient company (Yamatsu et al. 2015, J Nutr Sci Vitaminol (Tokyo))
A small group of adults; sleep was measured on an overnight brain-wave recording, with a questionnaire. Mood and anxiety were not assessed.
The leaf extract alone at 50 mg increased non-REM (deeper) sleep time by 7.6% but did not shorten the time to fall asleep. GABA alone shortened sleep latency by 5.3 minutes; the combination gave 4.3 minutes and 5.1% more non-REM sleep, so it was no better than either ingredient alone. Participants said they noticed effects on a questionnaire. A single small study of sleep traces.
Open (unblinded) randomized crossover intervention in 160 adults testing L-theanine, GABA, Apocynum venetum leaf extract (50 mg/day) and L-serine, with surveys of sleep problems (Imafuku et al. 2023, Nutrients)
160 adults; self-reported sleep problems and life habits were surveyed before and during supplementation.
All four supplements, including the leaf extract at 50 mg a day, significantly eased self-reported sleep problems, and which people improved varied with their habits and baseline sleep. The study was open-label with no placebo and relied on self-rating, so improvement cannot be firmly attributed to the supplement rather than expectation.
Animal and laboratory study of the branded Apocynum venetum leaf extract using a pentobarbital sleep test, sleep-architecture analysis, GABA-A binding assays and molecular docking; includes authors from the ingredient maker (Kim et al. 2025, J Ethnopharmacol)
Mice (in vivo), plus in vitro receptor-binding and in silico docking work. No people were studied.
The extract reduced sleep latency dose-dependently and lengthened non-REM sleep in mice, and repeated dosing kept working without withdrawal signs. In binding assays it had affinity for the benzodiazepine site of the GABA-A receptor, and flumazenil reversed the sleep effect in mice. An animal and laboratory mechanism study, not evidence of a sleep effect in people.
Animal study of a flavonoid extract of Apocynum venetum leaves in mouse behavior tests, with measurement of brain monoamines (Zheng et al. 2013, J Ethnopharmacol)
Mice given the extract by mouth, assessed in the forced-swim, tail-suspension and open-field tests.
At 50 and 100 mg/kg the extract lowered immobility in the forced-swim and tail-suspension tests without changing general movement, and raised noradrenaline and dopamine and their metabolites in the hippocampus; dopamine-receptor blockers prevented the effect. These are animal behavior models of low mood, not measurements in people.