Benefits
Sleep quality ratings in adults with poor sleep
In a 90-day placebo-controlled trial of 80 adults with poor sleep (71 completers analyzed), 400 mg taken 1 hour before bed raised a 0 to 10 sleep quality rating, the main outcome, more than placebo (6.5 versus 5.5). Pittsburgh sleep index total, time to fall asleep and sleep efficiency scores also improved more. The maker funded the trial.
Sleep measured by wrist actigraphy
In the same trial, a wrist actigraph showed shorter time to fall asleep, higher sleep efficiency (93.3% versus 91.5%) and less time awake after falling asleep than placebo at 90 days. Total sleep time, time in bed and the number of awakenings did not differ, so the extract did not lengthen sleep.
Night-time melatonin levels
Night-time blood melatonin rose in the extract group and ended higher than placebo after 90 days (199.7 versus 174.7 pg/mL, p = 0.048), while morning cortisol did not change in either group. Values varied widely between people, and this is one maker-funded result rather than an established effect.
Perceived stress and cortisol in adolescents
In a 12-week placebo-controlled trial in 42 healthy adolescents aged 12 to 16 with sleep and stress complaints, 400 mg before bed lowered perceived stress scores, a primary outcome, more than placebo from the first month, and morning salivary cortisol was lower than placebo at 12 weeks. Eight of ten authors worked for the maker or the companies that ran the study.
Sleep questionnaire scores in adolescents
In the same adolescent trial, scores on the Adolescent Sleep Wake Scale, a primary outcome, rose more than with placebo from the first month (4.5 versus 3.5 at 12 weeks on a 1 to 6 scale). Sleep was measured only by questionnaire, the groups differed in their mix of boys and girls, and the paper is not indexed in PubMed.
Stress and anxiety scores in adults
In adults with poor sleep, state anxiety scores fell more with the extract than placebo over 90 days (p = 0.037), a secondary result, while perceived stress and trait anxiety did not differ. In 40 adults with moderate stress, perceived stress and cortisol fell from baseline after 8 weeks but did not differ from placebo (cortisol p = 0.08).
REM sleep share and sleep scores in stressed adults
In 40 adults with moderate stress and poor sleep, 8 weeks of 400 mg raised the share of REM sleep on a Fitbit tracker above placebo (23.0% versus 19.0%). Pittsburgh sleep scores improved from baseline in the extract group but differed from placebo only in women, and the two groups started with unequal scores.
Mechanism of action
Verbascoside and the GABA-A benzodiazepine site
In mice given injections of lemon verbena extracts or pure verbascoside, the main RelaxPLX polyphenol, pentobarbital sleep lasted longer and anxiety-like behavior fell. Flumazenil, which blocks the benzodiazepine site of the GABA-A receptor, reduced these effects. RelaxPLX itself was not tested, and the route was not oral.
Adenosine A1 and GABA-A receptor expression in mice
In mice, an oral lemon verbena extract manufactured by Monteloeder (not named as RelaxPLX) shortened the time to fall asleep after a sedative, increased REM and non-REM sleep on EEG, and raised brain adenosine A1 receptor levels and gene activity of GABA-A receptor subunits. These are animal findings and have not been measured in people taking RelaxPLX.
Night-time melatonin in one human trial
In the 90-day adult trial, night-time blood melatonin rose with the extract and ended higher than with placebo, which the authors propose as one explanation for the sleep results. Morning cortisol did not change. It has been measured in a single trial, so it remains a possible mechanism.
Clinical trials
Randomized, double-blind, placebo-controlled parallel trial at one Spanish university; 400 mg lemon verbena extract (at least 24% verbascoside and 28% phenylpropanoids) supplied by Monteloeder, 1 hour before bed for 90 days; the paper does not use the RelaxPLX name, but the maker lists this trial for RelaxPLX and a later Monteloeder paper calls it the same extract; funded by Monteloeder, and three authors were its employees; registered NCT06154629 in November 2023, after the paper's stated April to July 2023 study period, primary outcome a 0 to 10 sleep quality rating (Pérez-Piñero et al. 2024, Nutrients)
80 adults with poor sleep (Pittsburgh score above 5) and moderate anxiety were randomized; only the 71 completers were analyzed (33 of 40 on extract, 38 of 40 on placebo), average age 29.5.
The primary sleep quality rating rose more than placebo (6.5 versus 5.5, p = 0.021). Pittsburgh total (5.8 versus 7.4, p = 0.008), sleep latency and sleep efficiency scores improved more, and actigraphy showed better sleep latency, efficiency and wake time after sleep onset; total sleep time did not differ. State anxiety fell more (p = 0.037); perceived stress and cortisol did not differ. Night-time melatonin rose (p = 0.048).
Randomized, double-blind, placebo-controlled parallel trial; one 400 mg capsule of lemon verbena extract (at least 24% verbascoside, named in the methods as PLX or RelaxPLX and provided by Monteloeder) 1 to 2 hours before bed for 8 weeks, then a 4-week washout; no external funding stated, but Monteloeder took part in designing the protocol and three authors were its employees; registered retrospectively as NCT05128812 (Martínez-Rodríguez et al. 2022, Nutrients)
40 adults with moderate perceived stress and poor sleep (20 per group), average age 38.7; the extract group was younger and heavier, had more men and started with better sleep scores.
Perceived stress fell 10.7% from baseline at 8 weeks in the extract group but did not differ from placebo, and cortisol fell 15.6% from baseline with only a trend versus placebo (p = 0.08). Pittsburgh sleep scores improved from baseline but differed from placebo only in women. On a Fitbit tracker, REM sleep share rose above placebo (23.0% versus 19.0%); deep sleep and awakenings changed only versus baseline. The paper names no primary outcome.
Randomized, double-blind, placebo-controlled parallel trial at one Italian center; 400 mg RelaxPLX (named in the methods, provided by Monteloeder) as two capsules 1 hour before bed for 12 weeks; primary outcomes were the Adolescent Sleep Wake Scale, the Perceived Stress Scale for Children and salivary cortisol; no external funding stated, though a Monteloeder author is credited with funding acquisition; four authors worked for Monteloeder and four for the companies that ran the study; no registry number given; not indexed in PubMed (Navarro et al. 2025, Appl Sci)
44 healthy adolescents aged 12 to 16 with sleep and stress complaints were randomized and 42 completed (21 per group); 62% of the extract group and 29% of the placebo group were boys.
Sleep scale scores rose more than placebo from month 1 (4.5 versus 3.5 at 12 weeks) and perceived stress scores fell more (12.9 versus 17.2). Morning salivary cortisol was lower than placebo only at 12 weeks (0.45 versus 0.61 µg/dL). In a secondary measure, a blinded psychologist judged the product effective for 86% on extract versus 19% on placebo. Results are reported as means with standard errors and without exact p values.