Nervous System

In mice an aqueous extract produced an anticonflict effect at a low dose of 25 mg/kg, separable from sedation, and both the anxiolytic and the sedative effects were abolished by flumazenil, implicating the benzodiazepine site directly ^{21,22Reference 21Rolland et al. · 1991Behavioural effects of the American traditional plant Eschscholzia californica: sedative and anxiolytic propertiesView study →Reference 22Fedurco et al. · 2015Modulatory effects of Eschscholzia californica alkaloids on recombinant GABA-A receptorsView study →}.

The only RCT tested a fixed combination of California poppy, hawthorn, and magnesium against placebo in mild-to-moderate generalized anxiety disorder ^{23Reference 23Hanus et al. · 2004RCTDouble-blind, randomised, placebo-controlled study of a fixed combination of Crataegus oxyacantha and Eschscholtzia californica and magnesium in mild-to-moderate anxietyView study →}.

No published trial has tested the herb alone in humans, so its individual contribution and a monotherapy dose are both unknown.

The mechanism is well defined. Honokiol potentiates the benzodiazepine site of GABA-A and promotes non-REM sleep in mice ^{25Reference 25Qu et al. · 2012AnimalHonokiol promotes non-rapid eye movement sleep via the benzodiazepine site of the GABA-A receptor in mice — animal modelView study →}.

Every trial tested a two-herb proprietary blend in small, mostly female cohorts. There is no RCT of magnolia bark alone, and trait anxiety was unaffected.

The only single-herb human study, a randomized, double-blind, placebo-controlled crossover feasibility RCT in 12 people at 2 g/day for four weeks, significantly improved Pittsburgh Sleep Quality Index score with parallel gains in total sleep time, efficiency, and onset latency ^{26Reference 26Shergis et al. · 2021RCTMedicinal seeds Ziziphus spinosa for insomnia — randomised, placebo-controlled, cross-over feasibility clinical trialView study →}. Larger positive data all test zizyphus inside multi-herb formulas, where a nine-trial meta-analysis showed subjective improvement (SMD −0.58) ^{27Reference 27Yang et al. · 2023Meta-analysisThe herbal medicine Suanzaoren (Ziziphi Spinosae Semen) for sleep quality improvements — systematic review and meta-analysisView study →}.

Three separate constituents converge on sleep, including spinosin via postsynaptic 5-HT1A ^{28Reference 28Wang et al. · 2010AnimalPotentiating effect of spinosin, a C-glycoside flavonoid of Semen Ziziphi spinosae, on pentobarbital-induced sleep may be related to postsynaptic 5-HT1A receptors — rat in vivoView study →} and jujuboside A via GABAergic modulation of the paraventricular thalamus ^{29Reference 29Wang et al. · 2025AnimalJujuboside A in ameliorating insomnia in mice via GABAergic modulation of the PVT — mouse in vivoView study →}.

Isolated-compound doses do not transfer to the dry-fried whole-seed decoction the tradition actually uses.

A valerian and hops combination gave modest benefit against diphenhydramine and placebo, and Ze 91019 increased objectively tracked sleep duration ^{30,31Reference 30Morin et al. · 2005RCTValerian–hops combination and diphenhydramine for treating insomnia — randomised placebo-controlled clinical trialView study →Reference 31Schicktanz et al. · 2025RCTEffects of a valerian–hops extract combination (Ze 91019) on sleep duration and daytime cognitive and psychological parameters in occasional insomnia — randomised controlled feasibility trialView study →}.

The mechanism is unusual. The active is a degradation product of the bitter α-acids, 2-methyl-3-buten-2-ol, which forms on storage and enhances GABAergic inhibition ^{32Reference 32Franco et al. · 2012The sedative effects of hops (Humulus lupulus), a component of beer, on the activity/rest rhythm — animalView study →}, so a fresh hop is not the same medicine as an aged one.

A phase III RCT in 89 adults with mild-to-moderate depression found standardized SHR-5, at 340 or 680 mg/day for six weeks, significantly improved depression, insomnia, and emotional instability against placebo ^{43Reference 43Darbinyan et al. · 2007RCTClinical trial of Rhodiola rosea L. extract SHR-5 in the treatment of mild to moderate depression — randomised controlled trialView study →}.

A US head-to-head against sertraline in 57 people showed a smaller, non-significant antidepressant effect with far fewer adverse events ^{44Reference 44Mao et al. · 2015RCTRhodiola rosea versus sertraline for major depressive disorder — randomised placebo-controlled trialView study →}. Better tolerability at similar efficacy is a real clinical finding.

The proposed mechanism is MAO-A/B inhibition, shown ex vivo ^{45Reference 45Van Diermen et al. · 2009In vitroMonoamine oxidase inhibition by Rhodiola rosea L. roots — in vitroView study →}. Only two placebo-controlled RCTs exist, one underpowered, and there is no evidence in moderate-to-severe depression.

Rhodiola is an activator, dosed in the morning, and it can disturb sleep.

A Cochrane review pooled two adequate trials favouring the precursor over placebo but judged the evidence insufficient, while later small RCTs matched fluoxetine and fluvoxamine ^{46,47Reference 46Shaw et al. · 2001Systematic reviewTryptophan and 5-hydroxytryptophan for depression — Cochrane systematic reviewView study →Reference 47Jangid et al. · 2013RCTComparative study of efficacy of l-5-hydroxytryptophan and fluoxetine in first depressive episode — randomised double-blind trialView study →}. A challenge-model RCT found 200 mg 5-HTP blunted the reaction to a CO₂ panic challenge in people with panic disorder ^{48Reference 48Schruers et al. · 2002RCTAcute L-5-hydroxytryptophan administration inhibits carbon-dioxide-induced panic in panic disorder patients — randomised controlled trialView study →}.

Every trial used purified 5-HTP, not whole seed extract. This is a supplement’s evidence borrowed by a herb.

Serotonergic drug interactions apply in full.

A single 25 mg dose of the standardized Zembrin extract reduced amygdala reactivity to threat and weakened amygdala-hypothalamus coupling on fMRI, a plausible neural signature of a calmer stress response ^{49Reference 49Terburg et al. · 2013Acute effects of Sceletium tortuosum (Zembrin), a dual 5-HT reuptake and PDE4 inhibitor, in the human amygdala and its connection to the hypothalamus}.

Its mesembrine-type alkaloids act as serotonin-reuptake inhibitors, and the reported effect is a lift of low mood back toward baseline rather than an elevation of normal mood ^{50Reference 50Harvey et al. · 2011Pharmacological actions of the South African medicinal and functional food plant Sceletium tortuosum and its principal alkaloids}.

There is no depression or anxiety RCT, and the mechanistic rationale rests on a proprietary extract.

A double-blind placebo-controlled pilot RCT in mild Alzheimer’s found erinacine-A-enriched mycelial capsules, 1,050 mg/day for 49 weeks, improved MMSE and daily-living scores ^{58Reference 58Li et al. · 2020RCTPrevention of early Alzheimer’s disease by erinacine A-enriched Hericium erinaceus mycelia — randomised, double-blind, placebo-controlled pilot trialView study →}, resting on a neurotrophic mechanism in which hericerin derivatives activate a pan-neurotrophic pathway in hippocampal neurons ^{59Reference 59Martínez-Mármol et al. · 2023In vitroHericerin derivatives activate a pan-neurotrophic pathway in central hippocampal neurons — in vitro and mouse studyView study →}.

Its mood evidence is separate and thinner. Two small trials reported reduced depression, anxiety, and sleep disturbance, one with raised pro-BDNF ^{60Reference 60Vigna et al. · 2019Clinical trialHericium erinaceus improves mood and sleep disorders in patients affected by overweight or obesity — controlled trialView study →}.

The Alzheimer’s trial used a mycelial erinacine-A extract that does not correspond to fruiting-body powders or to culinary use.

A 16-week RCT found saffron 30 mg/day improved ADAS-cog scores against placebo in mild-to-moderate Alzheimer’s ^{61Reference 61Akhondzadeh et al. · 2010RCTSaffron in the treatment of patients with mild to moderate Alzheimer’s disease — 16-week randomised, placebo-controlled trialView study →}, a 12-month trial found it equivalent to memantine in moderate-to-severe disease ^{62Reference 62Farokhnia et al. · 2014RCTComparing the efficacy and safety of Crocus sativus L. with memantine in patients with moderate to severe Alzheimer’s disease — double-blind randomised clinical trialView study →}, and a meta-analysis of four RCTs found it superior to placebo and no different from donepezil or memantine ^{63Reference 63Ayati Z et al. · 2020Meta-analysisSaffron for mild cognitive impairment and dementia — systematic review and meta-analysis of randomised clinical trialsView study →}.

The trials are small, short relative to the disease course, and concentrated in one region, and whether anything beyond symptoms is modified is unknown.

Saffron also carries a substantial antidepressant literature, a separate body of evidence from the cognitive work.

Healthy-adult memory and attention trials support an acetylcholinesterase-inhibition mechanism ^{65Reference 65Scholey et al. · 2008RCTAn extract of Salvia (sage) with anticholinesterase properties improves memory and attention in healthy older volunteers — randomised controlled trialView study →}.

Samples are small and extracts heterogeneous across the literature, and the effect in healthy adults is acute and modest.

In healthy older adults, a standardized extract improved cognitive performance with anxiety and heart rate falling alongside ^{66Reference 66Calabrese et al. · 2008RCTEffects of a standardized Bacopa monnieri extract on cognitive performance, anxiety and depression in the elderly — randomised, double-blind, placebo-controlled trialView study →}, a real if modest nootropic signal over 12 weeks.

The pivotal disease test, a phase-2b RCT of Brahmi against donepezil in Alzheimer’s and mild cognitive impairment, was terminated early and found no significant ADAS-Cog difference ^{67Reference 67Prabhakar et al. · 2020RCTEfficacy of Bacopa monnieri (Brahmi) and donepezil in Alzheimer’s disease and mild cognitive impairment — randomised double-blind phase-2b trial (terminated)View study →}, despite extensive animal work on amyloid, tau, and cholinergic protection.

Bacopa is a cognition-support herb in healthy ageing rather than a dementia treatment.

A six-week randomized, double-blind, placebo-controlled trial of the standardized extract OciBest in 150 people significantly reduced self-rated stress symptoms, including forgetfulness, exhaustion, sleep, and sexual problems, against placebo ^{74Reference 74Saxena et al. · 2012RCTEfficacy of an extract of Ocimum tenuiflorum (OciBest) in the management of general stress — randomised placebo-controlled trialView study →}.

A 2022 eight-week RCT of a different standardized extract in 100 people also improved stress and sleep measures ^{75Reference 75Lopresti et al. · 2022RCTA randomised, double-blind, placebo-controlled trial investigating the effects of a standardised Ocimum tenuiflorum extractView study →}.

The trials are small, use different preparations and doses, and rest on subjective symptom scales rather than on physiological stress markers.

The negative result is as informative as the positive ones. Adding 120 mg/day to stress-management training gave negligible extra benefit ^{78Reference 78Schaffler et al. · 2013RCTNo benefit adding Eleutherococcus senticosus to stress management training in stress-related fatigue — randomised controlled studyView study →}.

Effects are clearest only in people already fatigued or elderly, and no trial shows durable benefit in healthy adults.

Six placebo-controlled RCTs in 561 patients exist. The pivotal one, a stable supercritical-CO₂ extract standardized to parthenolide (MIG-99, 6.25 mg three times daily, n=170), cut migraine frequency by about 0.6 attacks per month against placebo, with no benefit on intensity or duration ^{80,81Reference 80Diener et al. · 2005RCTEfficacy and safety of 6.25 mg t.i.d. feverfew CO₂-extract (MIG-99) in migraine prevention — randomised, double-blind, placebo-controlled studyView study →Reference 81Pfaffenrath et al. · 2002RCTThe efficacy and safety of Tanacetum parthenium (feverfew) in migraine prophylaxis — double-blind, multicentre, randomised placebo-controlled dose-response studyView study →}.

A Cochrane review calls this some positive evidence of low quality ^{82Reference 82Wider et al. · 2015Systematic reviewFeverfew for preventing migraine — Cochrane systematic reviewView study →}.

The effect is small and extract-specific, and does not transfer to teas or whole-leaf powder.

It is migraine prophylaxis, taken preventively rather than to abort an attack, and null for tension-type headache.

A 10% peppermint-oil-in-ethanol solution dabbed on the forehead and temples eased tension-type headache in small double-blind trials, with relief reported comparable to paracetamol at 15 to 30 minutes ^{83,84Reference 83Göbel et al. · 1996RCTEffectiveness of Oleum menthae piperitae and paracetamol in therapy of headache of the tension type — randomised controlled trialView study →Reference 84Göbel et al. · 2016ReviewPeppermint oil in the acute treatment of tension-type headache — reviewView study →}. The proposed mechanism is menthol activating cold-sensitive TRPM8 receptors in the skin rather than any systemic action.

The evidence is a handful of older trials from essentially one research group, and the effect belongs to the topical oil rather than to oral use or tea.

No trial has tested willow for headache specifically. The use is a mechanistic extrapolation from proven salicylate analgesia.

Willow acts more slowly and more weakly than aspirin, and it carries the same salicylate cautions.

The calming effect belongs to cannabidiol rather than to the whole plant. In a double-blind RCT a single 600 mg oral CBD dose reduced anxiety during a simulated public-speaking test in people with social anxiety ^{91Reference 91Bergamaschi et al. · 2011RCTCannabidiol reduces the anxiety induced by simulated public speaking in treatment-naive social phobia patients — randomised controlled trialView study →}.

That dose is far above the 10 to 50 mg in most retail products, there is no chronic-treatment RCT, and high-THC cannabis can provoke anxiety and paranoia.

Its widespread use as a sleep aid is likewise preparation-dependent and self-limiting. Tolerance builds, REM is suppressed, and stopping can trigger rebound insomnia.