Oct 10, 2026

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

A woman in a cream linen shirt stands in a sunlit conservatory looking down at a lemon balm plant in a navy pot, a yellow watering can on the floor beside the door.

Lemon balm has a small and mixed trial record for sleep: a 2024 placebo-controlled crossover trial of a standardised extract 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 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.

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, which cannot show what lemon balm did alone.

Study	Design, people and length	Preparation	Result
Kennedy 2004⁷	Double-blind placebo crossover, 18 volunteers, 1 hour after dosing	Standardised extract, single 300 mg and 600 mg doses	Mood under a stress task, not sleep: calmer and less alert after 600 mg
Haybar 2018²	Double-blind placebo trial, 80 adults with stable angina, 8 weeks	3 g a day of dried herb	PSQI sleep disturbance, depression, anxiety and stress scores lower than placebo (p < 0.05)
Di Pierro 2024¹	Double-blind placebo crossover, two weeks per arm (full text); size not in the abstract	Standardised extract on a phospholipid carrier, 400 mg a day (full text)	Insomnia Severity Index 6.8 against 9.7 (p = 0.003); 87% against 30% reported better sleep; three authors work for or consult for the maker
Bano 2023⁸	Double-blind placebo trial, 100 distressed adults, 3 weeks	Phospholipid-carrier water extract, 200 mg twice a day	Depression, anxiety and stress scores better than placebo (p < 0.001); sleep score not in the abstract
Cases 2011⁹	Open-label, no placebo, 20 adults, 15 days	Standardised leaf extract; dose not in the abstract	Clinician-rated insomnia down 42%
Taavoni 2013¹⁰	Placebo trial, 100 women aged 50 to 60 with sleep complaints	Valerian plus lemon balm (combination)	PSQI lower than placebo
Müller 2006¹¹	Open multicentre study, no placebo, 918 children under 12	Valerian plus lemon balm (combination)	80.9% with sleep difficulty improved on parent and investigator ratings; manufacturer-run
Gutiérrez-Romero 2024³	Placebo trial, 64 adults with PSQI of 5 or more, 6 weeks	Theanine plus lemon balm, valerian and saffron (combination)	No significant difference on sleep efficiency (p = 0.49), sleep time (p = 0.66), wake after sleep onset (p = 0.33) or PSQI (p = 0.41)

Read together: the two placebo-controlled trials of lemon balm alone that reported a sleep result both favoured it, the combination studies describe blends rather than the herb, no trial used laboratory sleep recording and no two used the same preparation. A short, favourable, preparation-specific record, not yet repeated with the same extract in an independent group.

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 The single-dose crossover found 600 mg raised self-rated calmness during a stress battery,⁷ the three-week trial lower depression, anxiety and stress scores on 400 mg a day of a carrier-bound extract,⁸ and the angina trial the same direction on 3 g of dried herb.² Each measured a questionnaire score over weeks against placebo.

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 A cup of tea is a water infusion of a teaspoon or two of leaf with no trial on this page behind it, and a label figure means little unless it says what the extract is standardised to. The single-dose study measured one hour after the extract,⁷ and the sleep trials ran 14 days to 8 weeks with daily dosing,^1,2,8,9 so the record describes weeks of use, not one evening. 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 claims in the Great Britain nutrition and health claims register: "Only authorised claims in the Great Britain NHC register may be used in Great Britain".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 the nutrients that hold authorised claims (see 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. Neither label tells you how the trials turned out.

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 No human trial has measured thyroid hormones on lemon balm: a laboratory signal, not a clinical finding. 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 Ashwagandha has its own thyroid caution: can I take ashwagandha with levothyroxine.

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 says not all "natural" remedies are safe in pregnancy, 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 and the open-label child study and the blend trial none.^3,11 The only child study had no placebo; a child's sleep problem is a GP question. None reported 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 sets out the signs that need an appointment on their own.

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^1,2,8,9 and do not state the time of day, so "morning or night" has no trial answer; follow the product's label.

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, valerian and lemon balm products are registered herbal medicines.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, the fair answer to "what is the strongest herb for sleep".

Can you take lemon balm every night?

The longest placebo-controlled trial of lemon balm alone ran eight weeks at 3 g a day without serious side effects;² nothing longer has been published. 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

Di Pierro F, et al. Nutrients 2024. PubMed 39683592
Haybar H, et al. Clin Nutr ESPEN 2018. PubMed 29908682
Gutiérrez-Romero SA, et al. Sci Rep 2024. PubMed 38580720
Ghazizadeh J, et al. Phytother Res 2021. PubMed 34449930
Auf'mkolk M, et al. Endocrinology 1984. PubMed 6745167
Santini F, et al. J Endocrinol Invest 2003. PubMed 14759065
Kennedy DO, et al. Psychosom Med 2004. PubMed 15272110
Bano A, et al. Front Pharmacol 2023. PubMed 37927585
Cases J, et al. Med J Nutrition Metab 2011. PubMed 22207903
Taavoni S, et al. Complement Ther Clin Pract 2013. PubMed 24199972
Müller SF, Klement S. Phytomedicine 2006. PubMed 16487692
Department of Health and Social Care. Great Britain nutrition and health claims register, 19 May 2026. gov.uk
MHRA. Herbal medicines granted a traditional herbal registration, 27 October 2025. gov.uk
NHS. Levothyroxine. nhs.uk
NHS. Insomnia. nhs.uk
NHS. Medicines in pregnancy: herbal remedies. nhs.uk

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