Lemon balm has been used in calming remedies since at least the 16th century, when the physician Paracelsus recommended it for disorders of the nervous system. History alone isn't evidence — but lemon balm is one of the few traditional ingredients that has since been tested through modern, randomised, placebo-controlled trials. The results largely hold up.
The evidence on stress response
In one controlled study, participants received 300mg or 600mg of lemon balm extract, or a placebo, before completing a deliberately stressful multitasking exercise. Both doses reduced the negative mood associated with the stress, with the 600mg dose more effective for calmness — and without impairing performance on the task (summarised here).
A separate trial gave stressed adults 600mg daily for 15 days, tracking anxiety through validated questionnaires alongside sleep quality. Both measures improved over the study period (same source).
A more recent, registered trial
A 2023 randomised, placebo-controlled trial — registered on ClinicalTrials.gov — tested a standardised lemon balm extract in adults experiencing emotional distress and disrupted sleep. Researchers concluded the extract showed genuine calming effects and may support both areas (Bano et al., *Frontiers in Pharmacology*, 2023).
The proposed mechanism involves lemon balm's effect on an enzyme that regulates GABA, a calming neurotransmitter — a different route to relaxation than L-theanine, but a related outcome (same trial).
Looking across the wider evidence
A systematic review pooling multiple lemon balm trials for anxiety and low mood found broadly supportive results, while noting that study quality and dosing varied — a fair signal that the evidence is promising rather than fully settled ([Haybar et al., *Phytotherapy Research*).
What it isn't
Lemon balm is not a treatment for a diagnosed anxiety disorder, and shouldn't replace professional support for anyone experiencing that. The research cited here is largely in healthy adults managing everyday stress, a distinct context from clinical conditions.
Why it's relevant
Everyday stress — a demanding week, a difficult commute, the accumulation of small pressures — is precisely the context these studies measure. Lemon balm's evidence base speaks to that ordinary kind of tension, rather than any dramatic claim.
In brief
- Studies used doses of 300–600mg of standardised extract, well beyond what a cup of tea would provide.
- Mood effects appeared within hours in some studies; sleep improvements were measured over roughly 15 days.
- Generally well tolerated, though anyone on thyroid medication or sedatives should check with a doctor first.
- Often paired with L-theanine, given the two support calm through related but distinct pathways.
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Sources
1. 'Cortisol and Selected Botanicals', summarising randomised, placebo-controlled trials on lemon balm and stress. Read here
2. Bano, A. et al. (2023). 'The possible "calming effect" of subchronic supplementation of a standardised Melissa officinalis L. extract.' Frontiers in Pharmacology. Read on PMC
3. Haybar, H. et al. 'The effects of lemon balm on depression and anxiety: A systematic review and meta-analysis.' Phytotherapy Research. Read on Wiley