Does Lemon Balm Help You Sleep? Trials, Thyroid Caution, UK Rules

Lemon balm has a small and mixed trial record for sleep: a maker-run 2024 placebo-controlled crossover trial of a standardised extract in 30 adults brought insomnia severity scores to 6.8 against 9.7 on placebo; 80 people with stable angina taking 3 g of the dried herb a day for eight weeks reported less sleep disturbance than placebo; and a six-week company-funded trial of a blend of theanine, lemon balm, valerian and saffron in 64 adults was no better than placebo.^1,2,3 Its larger record is for anxiety: a 2021 meta-analysis found a pooled effect of -0.98 standard deviations against placebo, with high heterogeneity.⁴ Lemon balm holds no authorised health claim in Great Britain; the UK products that say "to aid sleep" are registered herbal medicines. Two laboratory studies found leaf extracts block thyroid-stimulating hormone from binding to its receptor, a caution for anyone with a thyroid condition, not a proven interaction.^5,6 The Wellgard sleep guide covers the habits the NHS puts first.

Sources checked on 30 October 2026.

What is lemon balm, and what is in the extract?

Lemon balm is Melissa officinalis, a mint-family herb taken as a tea, as dried herb in capsules, or as an extract standardised to its hydroxycinnamic acids, chiefly rosmarinic acid, which in the laboratory inhibits the enzyme that breaks down GABA; the 2024 trial authors note this effect "has not always been observed in a reproducible manner in humans".¹

Did lemon balm help sleep in trials?

Eight human studies are the ones people quote: four of lemon balm alone against placebo, one open-label, and three combinations.

Read together: the three placebo-controlled trials of lemon balm alone that reported a sleep result all favoured it, the combination studies describe blends rather than the herb, no trial used laboratory sleep recording and no two used the same preparation.

Did lemon balm help anxiety in trials?

The 2021 systematic review pooled randomised trials to October 2020 in people with symptoms of anxiety or depression: lemon balm lowered anxiety scores against placebo by a standardised mean difference of -0.98 (95% confidence interval -1.63 to -0.33) and depression scores by -0.47, with no serious side effects; the authors warn that heterogeneity was high and the trials few and varied.⁴

Lemon balm tea or extract: can you compare them?

Not by milligram. The trials used three different things: a standardised dry extract at 300 mg and 600 mg,⁷ 3 g a day of whole dried herb,² and carrier-bound extracts at 400 mg a day.^1,8 No trial on this page tested a cup of tea, and a label figure means little unless it says what the extract is standardised to. See also what to drink before bed.

Why do some UK lemon balm products say "to aid sleep" when supplements cannot?

Two sets of rules apply. A food supplement may use only the authorised claims in the Great Britain nutrition and health claims register.¹² The register, last updated in May 2026, has no entry for lemon balm or Melissa: its proposed botanical claims were never assessed and sit "on hold", neither authorised nor rejected. That is a statement about the register, not a verdict on the trials; in a blend, the usable wording belongs to nutrients with authorised claims (how to choose a melatonin-free sleep supplement in the UK).

Herbal medicines run on a separate scheme. The MHRA's list of traditional herbal registrations (27 October 2025) shows lemon balm leaf in four registered products: a single-herb capsule of 171 mg dry extract (equivalent to 684 to 1,026 mg of leaf) "for the temporary relief of symptoms of mild anxiety, to aid sleep and for mild digestive complaints, such as bloating and flatulence"; a valerian and lemon balm tablet "for the temporary relief of sleep disturbances due to symptoms of mild anxiety"; and two further combination products.¹³ A traditional herbal registration rests on long-standing traditional use rather than clinical trials, and its wording belongs to that medicine alone.

Is lemon balm safe, and who should ask first?

Thyroid conditions and levothyroxine. In 1984, freeze-dried water extracts of lemon balm blocked thyroid-stimulating hormone (TSH) from binding to human thyroid membranes in the laboratory;⁵ in 2003, lemon balm extract inhibited TSH signalling in cells carrying the human TSH receptor.⁶ The NHS levothyroxine page asks you to "tell your doctor if you're taking any other medicines, herbal remedies, vitamins or supplements",¹⁴ and the NHS lists an overactive thyroid among the causes of insomnia.¹⁵

Sedating medicines and alcohol. The single-dose trial recorded lower alertness after 600 mg,⁷ so anyone on sleeping tablets, sedating antihistamines, other sedating medicines or a sedating antidepressant (can you take sleep supplements with antidepressants?) mentions lemon balm to the pharmacist first; no interaction study exists. The NHS says: "Check with your doctor before taking anything for your sleep problems."¹⁵

Pregnancy and breastfeeding. No trial included pregnant or breastfeeding women; the NHS advises against herbal remedies when trying to get pregnant and asks you to tell your midwife, doctor or pharmacist about any you use.¹⁶

Side effects in the trials. The meta-analysis found no serious side effects,⁴ the three-week trial no serious adverse events,⁸ the blend trial no serious ones and the open-label child study none related to the product.^3,11 A child's sleep problem is a GP question. None of the trial abstracts reports liver results, so "is lemon balm hard on the liver" has no trial data either way. If sleep has been poor for months, changing your habits has not helped, or it is making daily life hard to cope with, the NHS says to see a GP;¹⁵ when to see a GP about sleep has the detail.

What we don't know

Whether lemon balm alone helps diagnosed insomnia: the placebo-controlled trials were small, used different preparations, measured sleep by questionnaire or wrist tracker, and the largest sleep effect came from a maker-run trial.^{1, 2, 8} Whether the thyroid signal seen in laboratory work happens in people has never been measured.^{5, 6}

Frequently asked questions

Will lemon balm make me sleepy straight away?

The only timed measurement is the single-dose trial: 18 volunteers rated themselves less alert one hour after 600 mg.⁷ The sleep trials ran 14 days to 8 weeks, one dosing 30 minutes before bed and others twice a day, so no trial compared morning with night.^1,2,8,9

Does lemon balm work with valerian?

Two studies tested the pair: 100 menopausal women scored better than on placebo,¹⁰ and 918 children improved in an open study with no placebo.¹¹ A four-herb blend containing both was no better than placebo over six weeks in 64 adults.³ None can say what lemon balm added; in the UK, one valerian and lemon balm tablet is a registered herbal medicine.¹³

Which is better for sleep, chamomile or lemon balm?

No trial has compared them. Both are on-hold botanicals in the GB register¹² with small placebo-controlled records, and the preparations differ too much to rank by dose. Does chamomile help you sleep gives chamomile the same treatment; which sleep supplements have evidence behind them ranks every ingredient by trial count and size.

Can you take lemon balm every night?

The longest placebo-controlled trial of lemon balm alone ran eight weeks at 3 g a day;² nothing longer has been published, and the pooled review found no serious side effects.⁴ The NHS says pharmacy sleep aids containing valerian or lavender "may help you sleep better for 1 to 2 weeks" and "should not be taken for any longer".¹⁵

Sources

1. Di Pierro F, et al. Nutrients 2024. Randomised double-blind placebo-controlled crossover, 30 adults, 2 weeks per arm; three authors work for or consult for the maker. PubMed 39683592
2. Haybar H, et al. Clin Nutr ESPEN 2018. Double-blind placebo-controlled trial, 80 adults with stable angina, 8 weeks; funding not stated on PubMed. PubMed 29908682
3. Gutiérrez-Romero SA, et al. Sci Rep 2024. Randomised placebo-controlled trial, 64 adults, 6 weeks; funded by a food company. PubMed 38580720
4. Ghazizadeh J, et al. Phytother Res 2021. Systematic review and meta-analysis of randomised trials; funding not stated on PubMed. PubMed 34449930
5. Auf'mkolk M, et al. Endocrinology 1984. Laboratory study; funding not stated on PubMed. PubMed 6745167
6. Santini F, et al. J Endocrinol Invest 2003. Cell study; funding not stated on PubMed. PubMed 14759065
7. Kennedy DO, et al. Psychosom Med 2004. Randomised double-blind crossover, 18 volunteers, single doses; funding not stated on PubMed. PubMed 15272110
8. Bano A, et al. Front Pharmacol 2023. Randomised double-blind placebo-controlled trial, 100 adults, 3 weeks; no conflicts declared. PubMed 37927585
9. Cases J, et al. Med J Nutrition Metab 2011. Open-label pilot, 20 adults, 15 days; funding not stated on PubMed. PubMed 22207903
10. Taavoni S, et al. Complement Ther Clin Pract 2013. Placebo-controlled trial, 100 women aged 50 to 60; funding not stated on PubMed. PubMed 24199972
11. Müller SF, Klement S. Phytomedicine 2006. Open multicentre study, 918 children; run by the manufacturer. PubMed 16487692
12. Department of Health and Social Care. Great Britain nutrition and health claims register. Official register, last updated 19 May 2026. gov.uk
13. MHRA. Herbal medicines granted a traditional herbal registration. Official list dated 27 October 2025. gov.uk
14. NHS. Levothyroxine. Page last reviewed 6 July 2026. nhs.uk
15. NHS. Insomnia. Page last reviewed 19 March 2024. nhs.uk
16. NHS. Medicines in pregnancy: herbal remedies. Page last reviewed 5 September 2022. nhs.uk

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