Reviewing 5 popular sleep supplements

By Nutritank Writing Team

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Written by Lizzie Davies. Lizzie is a final year student dietitian at King’s College London. Her current interests in dietetics include women’s health and cystic fibrosis. In her spare time, she loves to bake and cook, and volunteers in the charity sector. Find her on Instagram @lizziedietetics.


Sleep has been a popular topic especially on social media, and thus Nutritank has hosted a series of webinars on sleep including sleep and mental wellbeing and sleep and lifestyle. Sleep problems and insomnia are common, and a topic that might arise in daily conversation or in clinic is supplements for sleep, and navigating the extensive variety of supplement options might be confusing. A popular wellness retailer lists over 80 items under the sleep and relaxation subcategory, so this may easily overwhelm patients as well as having the potential to become extremely costly. Below is a brief overview of some of the common supplements used for sleep that have undergone some research.

Valerian Root

Valerian root is a herbal supplement that has long been used as a sedative, especially to treat insomnia. There are over 200 valerian species worldwide with V. officinalis being the most well established in sleep disorders (1), it is thought of as being relatively safe with side effects being nausea and abdominal cramps. A systematic review and meta-analysis conducted in 2020 showed that valerian showed good benefits in sleep promotion and anxiolytic effects (anti-anxiety) which is linked to sleep, however, is not known exactly what the underlying mechanisms for this are. Although V. officinalis showed good results, in sub analysis it was found that outcomes were not reliable in other herbal extracts of valerian (1). Interestingly, valerian has also been studied in the context of postoperative sleep disturbances and showed good results in a retrospective cohort analysis (2).


Vitamin D

Low vitamin D is extremely common especially in the UK where in the autumn and winter months supplementation is necessary to get the daily recommendation. Along with a host of other poor health outcomes, a deficiency of vitamin D is associated with sleep disorders and poor sleep quality including nocturnal awakenings and shorter sleep duration (3). There are some theories behind this association such as the potential role of vitamin D in the regulation of melatonin, which is a hormone associated with sleep and is another form of supplementation discussed later. A systematic review of 19 studies suggests a potentially beneficial role of vitamin D supplementation in sleep quality, but the quality of studies was low and thus the authors recommend taking the findings with caution. However, it is certainly beneficial to optimise vitamin D levels for general health and it may have potential to positively impact sleep, furthermore vitamin D supplements are widely available and affordable.



Melatonin is possibly one of the most widely known supplements for sleep. It is a hormone that is naturally occurring in the body, it acts by regulating sleep with rising levels at night-time and baseline levels during the day. It can be prescribed on the NHS for sleep problems, usually used for a short term and is thought to be quite safe with few side effects. As melatonin levels are naturally reduced as we age (4), it is more commonly prescribed in older adults. Interestingly, it is produced in response to darkness perceived by the retina, therefore there is a hypothesis that artificial blue lights used at night can affect the levels of melatonin in the body and cause insomnia (5). Melatonin supplementation has shown significant benefit for sleep quality in some studies (6, 7), but there was high heterogeneity. More research is needed to assess where melatonin fits into treatment plans for patients, but it could be worth trialling in some patient groups. Melatonin is not authorised over the counter in the UK, however it is in other countries like the US and Canada.



Magnesium is sometimes discussed as being beneficial for improving sleep and insomnia, however the evidence base is limited and the small number of RCTs show contradictory findings (8). There are several possible mechanisms for magnesium benefiting sleep including having relaxant and anti-depressant effects as well as increasing melatonin and reducing cortisol levels. There may be benefits of magnesium in treating restless leg syndrome that is associated with poor sleep, but again the evidence is scarce and inconclusive (9).

Amino acids

Supplementation of several amino acids have been studied in sleep including glycine, tryptophan and l-theanine. All 3 of the amino acids listed have some evidence to support efficacy, but not enough to support use in clinical practise. L-theanine has shown some positive improvements in anxiety and stress related symptoms, it can be found in a dietary supplement form or in green tea extracts. Tryptophan is sometimes considered a natural hypnotic or sedative, and is the precursor of serotonin (10), there is some evidence to support its use in sleep but more studies are needed.



There are a lot of supplements on the market for sleep, more than what is briefly discussed here. Research in supplements and sleep is in its infancy, and there are a lack of recommendations for clinical practise even in more widely used supplements like melatonin, as there are only NICE guidance for over patients over 55. Sleep problems and insomnia can greatly affect a patient’s quality of life and thus people commonly purchase supplements over the counter or from health stores. It is important to educate patients on the potential side effects of herbal supplements, and to make sure there are no contraindications for the patient and ensure that they are taking them safely.


Useful websites:

The Sleep Charity



  1. Shinjyo N, Waddell G, Green J. Valerian Root in Treating Sleep Problems and Associated Disorders-A Systematic Review and Meta-Analysis. J Evid Based Integr Med. 2020;25:2515690×20967323.
  2. Winter AS, Haverkamp C, Gratzke C, Huber R, Lederer AK. Valerian and postoperative sleep: a retrospective cohort analysis of gynecological, urologic, and general surgical patients. Sleep. 2022;45(10).
  3. Abboud M. Vitamin D Supplementation and Sleep: A Systematic Review and Meta-Analysis of Intervention Studies. Nutrients. 2022;14(5).
  4. Poza JJ, Pujol M, Ortega-Albás JJ, Romero O. Melatonin in sleep disorders. Neurologia (Engl Ed). 2022;37(7):575-85.
  5. Minich DM, Henning M, Darley C, Fahoum M, Schuler CB, Frame J. Is Melatonin the “Next Vitamin D”?: A Review of Emerging Science, Clinical Uses, Safety, and Dietary Supplements. Nutrients. 2022;14(19).
  6. Chan V, Lo K. Efficacy of dietary supplements on improving sleep quality: a systematic review and meta-analysis. Postgrad Med J. 2022;98(1158):285-93.
  7. Fatemeh G, Sajjad M, Niloufar R, Neda S, Leila S, Khadijeh M. Effect of melatonin supplementation on sleep quality: a systematic review and meta-analysis of randomized controlled trials. J Neurol. 2022;269(1):205-16.
  8. Arab A, Rafie N, Amani R, Shirani F. The Role of Magnesium in Sleep Health: a Systematic Review of Available Literature. Biol Trace Elem Res. 2023;201(1):121-8.
  9. Marshall NS, Serinel Y, Killick R, Child JM, Raisin I, Berry CM, et al. Magnesium supplementation for the treatment of restless legs syndrome and periodic limb movement disorder: A systematic review. Sleep Med Rev. 2019;48:101218.
  10. Sutanto CN, Loh WW, Kim JE. The impact of tryptophan supplementation on sleep quality: a systematic review, meta-analysis, and meta-regression. Nutrition Reviews. 2021;80(2):306-16.



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