Four ingredients, without borrowed certainty
Research on one ingredient cannot prove the effect of a finished multi-ingredient product. Study populations, doses, extracts and outcomes differ.
Glycine
Two small human studies examined 3g before bedtime. One used sleep recordings in volunteers with unsatisfactory sleep; another studied next-day fatigue during partial sleep restriction. Both are useful signals, but neither is large enough to establish a dependable sleep outcome.
L-theanine
A 2025 review included 19 articles reporting randomised trials with 897 participants and found small improvements in some subjective sleep outcomes. The authors also found too few studies of pure L-theanine to settle the best dose or duration. A separate 30-person crossover trial studied 200mg daily for four weeks.
Magnesium
A 2025 placebo-controlled trial in 155 adults reporting poor sleep found a small improvement after four weeks of 250mg elemental magnesium as bisglycinate. A 2021 review found only three older-adult trials and rated the evidence low to very low quality. Separately, magnesium has authorised UK nutrient-function claims, which is not the same as a claim to treat insomnia.
2025 bisglycinate trial · 2021 systematic review · GB claims register
Ashwagandha
A 2021 review of five randomised trials involving 400 adults found a small overall sleep effect and called for more long-term safety data. A separate 2020 placebo-controlled trial used a standardised 120mg extract in 150 adults for six weeks. Extract, dose and duration vary, so results should not be transferred automatically to every formula.
