Supplements for sleep
Magnesium glycinate, glycine, L-theanine and ashwagandha: what the trials say, who each suits, and what to skip. UK made, practitioner grade.
How to choose a sleep supplement
Falling asleep faster, staying asleep and waking clearer. Magnesium, glycine, L-theanine and ashwagandha each help in a different way, so pick by what your nights look like: magnesium for a body that will not settle, glycine for deeper sleep, theanine for a busy mind, ashwagandha for stress that follows you to bed.
Why these
Magnesium Bisglycinate Capsules: Helps you fall asleep and stay asleep, without the bowel effect of other forms. The best-evidenced sleep supplement; give it two to four weeks.
Glycine Capsules: Deeper sleep and a clearer head in the morning, from the first night in the trials. Take 3 g about an hour before bed.
L-Theanine Capsules: Switches off a busy mind without making you drowsy. The calming amino acid from green tea, for the evening wind-down.
Ashwagandha: Takes the edge off stress so sleep comes more easily. An adaptogen root that builds over weeks; morning or evening.
Unplug: One capsule that does the wind-down for you: L-theanine, magnesium and zinc, with no grogginess the next morning.
Read the evidence
Magnesium for sleep: week by week · How long does glycine take to work? · How long does ashwagandha take to work?
If you take prescribed medicines, are pregnant or breastfeeding, or have a diagnosed condition, talk to your GP or pharmacist first. Not sure which fits? Ask Nutri365, the Nutri Tailor AI health expert, which checks for interactions and contraindications.
Common questions
How long does magnesium take to work for sleep?
Gradually. Possible early effects in the first week, most measurable change by weeks two to four, and a fair verdict at four to eight weeks. The pooled trials are in older adults with insomnia, so the effect in younger people is less certain.
Can I take magnesium and glycine together?
Yes. They work in different ways and the trials used them separately, so there is no interaction to plan around; many people take both in the evening.
Is melatonin sold as a supplement in the UK?
No. Melatonin is prescription-only in the UK, so it is not sold here and does not appear on this page.
Written by Nutri Tailor from the Health Reference Library. Last checked 6 September 2026. General information, not personal advice.