What Supplements Help With Sleep? A Guide to the Evidence
Supplements for sleep represent one of the fastest-growing segments of the UK wellness market. The question of what supplements help with sleep is asked by millions of people, many of whom have tried sleep hygiene advice and found it insufficient, or who want additional support during periods of disrupted sleep. This guide covers which supplements have meaningful evidence, which carry more hype than substance, and what UK law permits companies to claim.
Why Supplements Should Be a Secondary Intervention for Sleep
Before considering supplements, it is worth being clear about their role in the sleep evidence hierarchy. Cognitive behavioural therapy for insomnia (CBTi) is the most evidence-supported intervention for chronic insomnia, rated more effective than medication in long-term outcomes by multiple systematic reviews. Sleep hygiene, consistent sleep timing, reduced evening screen exposure, managing caffeine, and addressing stress and anxiety are all evidence-based steps that precede supplementation.
Supplements work best as support for the conditions that make sleep possible, not as direct sleep inducers. The distinction matters both for managing expectations and for using them appropriately.
Supplements With Consistent Evidence for Sleep Support
Magnesium: The supplement with the strongest and most consistent evidence base for sleep support. Magnesium is involved in the regulation of GABA receptors, the central inhibitory neurotransmitters that facilitate the nervous system's transition from arousal to rest. Multiple randomised controlled trials have shown that magnesium supplementation, particularly in adults with low baseline levels, improves subjective sleep quality, reduces sleep onset time, and increases total sleep duration. Magnesium glycinate and magnesium threonate are the preferred forms.
This is also where AEQUIL®’s SLEEP+ Experience can be introduced as part of an evening wellness routine, offering a melatonin-free format that includes a supplement and wellbeing patch for those creating a more intentional night-time ritual.
L-Theanine: An amino acid found naturally in green tea. Several published trials have demonstrated its ability to reduce pre-sleep anxiety and promote the kind of calm, non-sedated state that facilitates sleep onset. It appears to work by increasing alpha brain wave activity, associated with relaxed alertness. It is generally well-tolerated and can be taken alongside magnesium.
Ashwagandha: The most studied adaptogen in sleep research. Standardised KSM-66 and Sensoril extracts have demonstrated reductions in self-reported stress, improvements in sleep quality scores, and reductions in salivary cortisol in stressed adults across multiple RCTs. It works best in people whose poor sleep quality is driven by elevated stress and HPA axis dysregulation rather than purely physiological sleep architecture issues.
Glycine: An amino acid with published evidence for improvements in slow-wave (deep) sleep and reduced next-day fatigue. The mechanism appears to involve peripheral vasodilation and a resulting drop in core body temperature, which is a key physiological signal for sleep consolidation. A dose of 3g before bed is what has been used in published studies.
A Note on Melatonin
Melatonin is the most-searched sleep supplement globally, and in many countries is available over the counter. In the UK, melatonin is a prescription-only medicine and cannot legally be purchased without a prescription. It cannot be ordered from UK-based retailers as a supplement. If you are considering melatonin, speak with your GP. Prescribed low-dose melatonin is available for specific indications, including jet lag and circadian rhythm disorders.
Supplements to Approach With Caution or Realistic Expectations
Valerian: One of the most historically used herbal sleep remedies in European tradition. The evidence is heterogeneous: some trials show benefit, others show no significant effect versus placebo. It is unlikely to cause harm, but expectations of consistent measurable effect should be modest. Some people report improvements in sleep quality; others notice nothing.
5-HTP and tryptophan: Precursors to serotonin and melatonin, respectively. Some published evidence for improvement in sleep onset and quality, but fewer high-quality RCTs than the options above. Not suitable for people taking antidepressants, particularly SSRIs or MAOIs, without clinical guidance.
AEQUIL®: Sensory Ritual Over Supplementation
Frédéric Roscop, AEQUIL®'s founder and a qualified osteopath, took a deliberate decision in designing Be Rested. A cosmetic patch is a sensory ritual: something to apply as part of the transition from an activated to a settled state. It works alongside supplements and lifestyle strategies, addressing the sensory and habitual dimension of the evening routine.
Disclaimer: This article is for informational purposes only and is not intended as medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional before beginning a new supplement regime. If you are experiencing persistent sleep problems, speak with your GP.