Objective/background: This study evaluated the feasibility of investigating the effect of a valerian and hops-based herbal medication (Ze 91019) on daytime cognitive performance, psychological parameters, and sleep measures in individuals with occasional sleep problems.
Methods: A randomized, double-blind, placebo-controlled study was conducted in 40 participants over a 21-day run-in period and a 21-day treatment period. Participants used Fitbit sleep trackers and completed daily online cognitive tests (i.e., reaction time and working memory), and surveys to assess subjective psychological outcomes (i.e., cognitive performance, stress levels, tiredness, mood, quality of life, and motivation).
Results: The study design proved feasible, with high adherence to the study protocol. Exploratory analyses revealed a statistically significant increase in sleep duration during the treatment period for participants using Ze 91019 compared to placebo (mean daily increase: 21.7 min, p = 0.019) without statistically significant effects on cognitive or psychological outcomes. Moreover, Ze 91019 statistically significantly increased the sleep duration of the shortest night in the treatment period by 48.7 minutes. The medication was well-tolerated.
Conclusions: The study design proved feasible, and Ze 91019 increased sleep duration without affecting daytime cognitive or psychological outcomes.
Trial registration: The trial has been preregistered at www.
Clinicaltrials: gov (NCT05684523).
Keywords: Ze 91019; cognition; feasibility study; fitbit charge 5; herbal medicine; hops; redormin; sleep; valerian.
© 2025 The Author(s). Brain and Behavior published by Wiley Periodicals LLC.