Lemon balm (Melissa officinalis) has a long history of traditional use for calming the nerves and promoting relaxation, but there is also a growing body of scientific evidence supporting its effects on the parasympathetic nervous system. The parasympathetic nervous system is responsible for the "rest and digest" response, and substances that promote its activity are often described as calming or anxiolytic.

Several clinical and preclinical studies have demonstrated that lemon balm extract and its constituents (notably rosmarinic acid) can have anxiolytic and mild sedative effects. Research has shown that lemon balm may enhance mood, promote calmness, and improve cognitive performance under stress. For example, a randomized controlled trial published in Phytotherapy Research (Kennedy et al., 2002) found that a single dose of lemon balm improved mood and increased calmness in healthy volunteers. Mechanistic studies suggest that lemon balm may modulate GABAergic activity, which is closely linked with parasympathetic activation.

While these studies support its use for nervous system relaxation and reducing stress, the evidence is mostly preliminary and based on small sample sizes. Larger, well-designed clinical trials are still needed to confirm these effects and fully elucidate the mechanisms involved. Nonetheless, current data provide a moderate scientific rationale for lemon balm's role in supporting the parasympathetic nervous system.