Lemon Balm (Melissa officinalis) and Anxiety or Insomnia: What Does the Evidence Actually Show?

Lemon balm (Melissa officinalis) is one of the oldest herbs traditionally used to calm "nerves" — mentioned in ancient medical texts, and present in European herbal medicine for centuries as an ingredient in teas, tinctures, and calming blends. Its popularity has never really waned, but for a long time it rested almost entirely on tradition and clinical observation rather than solid, randomized trials comparing it against placebo.

That has only started to change in the last decade, with a series of smaller clinical trials evaluating lemon balm for anxiety, low mood, and sleep quality — and, more importantly, with the first systematic meta-analysis of those trials, published in 2021. That meta-analysis is today the single most reliable source of knowledge on whether lemon balm actually works, and it's the main point of reference throughout this article.

It's worth flagging a distinction up front that will recur throughout this piece: the evidence for lemon balm's anti-anxiety and antidepressant effects is noticeably stronger than the evidence for its effect on sleep itself. These are two different questions that article headlines and supplement labels often blur into one, even though they really aren't the same thing.

Lemon balm contains compounds (including rosmarinic acid and terpenes such as citral and citronellal) studied for their effects on several brain signaling pathways at once. The one most often cited is the GABAergic system — through inhibition of the enzyme that breaks down gamma-aminobutyric acid (GABA), the brain's main inhibitory neurotransmitter, which in theory would produce an effect similar to, though much milder than, some anti-anxiety medications.

Beyond the GABAergic pathway, researchers also point to a possible effect on the cholinergic system (which could explain reports of improved cognitive function alongside a calming, rather than sedating, effect) and the serotonergic system, linked to mood regulation. An important caveat: most of these mechanisms come from animal or in-vitro studies — in humans, we see a clinical effect (described in the next section), but the exact mechanism behind it still isn't fully confirmed.

The effect size (an SMD close to -1.0 for anxiety) is, statistically speaking, fairly large for a herbal intervention — for comparison, many anti-anxiety medications evaluated in meta-analyses land in the 0.3–0.6 SMD range. But a large effect in a meta-analysis with few trials and high heterogeneity tends to run inflated — the fewer trials feeding into an analysis, the greater the risk that one unusual trial's result strongly skews the pooled figure.

This article's title pairs anxiety and insomnia for good reason — in clinical practice these two problems often co-occur, and anxiety is one of the leading causes of trouble falling asleep. But the meta-analysis discussed above deals primarily with anxiety and depression symptoms, not directly with sleep quality — an important distinction that shouldn't be blurred away.

Evidence for lemon balm's effect on sleep itself comes mainly from single, small trials. One of the more frequently cited — a randomized, double-blind trial in 80 patients after coronary artery bypass surgery (Soltanpour et al., 2019, European Journal of Integrative Medicine) — found that seven days of taking 1.5 g of dried lemon balm leaf daily significantly improved sleep quality versus placebo (mean change in sleep score: 14.40±5.1 versus 7.52±4.4; p<0.001) and lowered anxiety (p=0.001). That's a promising result, but it comes from a narrow, specific population (postoperative, cardiac-surgery patients) over a short, seven-day observation period — it can't be generalized without reservation to chronic insomnia in otherwise healthy people.

This distinction has practical significance: if someone reaches for lemon balm purely for sleep, and their insomnia isn't anxiety-driven, disappointment with the effect doesn't necessarily mean "lemon balm doesn't work at all" — it may simply mean that, in that particular case, the underlying problem isn't the anxiety that lemon balm actually has documented effects on.

Lemon balm is one of the few "calming" herbs to have earned a real, if still modest, evidence base grounded in randomized trials rather than tradition alone. That's reason enough to take it more seriously than many other products in this category — provided the proportions are kept straight between what's actually been shown (an effect on anxiety and depression symptoms) and what marketing sometimes attributes to it (a universal "sleep aid").