Supplements for sleep and stress: what's studied and how to choose

How this section works

You won’t find “best sleep supplement” rankings here. For each ingredient we say what the studies showed, what dose was used and who it doesn’t suit. The iHerb links open a selection of the right form, so you compare brands and prices yourself.

Find your option: sleep and stress

Pick what bothers you to see where to start and which guide to read

What bothers you?

Shifted schedule Evening tension Low-magnesium diet Insomnia over 3 months

Where to start

Melatonin 0.5–1 mg

The best-studied option for falling asleep and jet lag.

Usual dose: 0.5–1 mg 30–60 minutes before bed

Prescription-only in the UK.

Melatonin on iHerb Read the guide

Where to start

Our sleep supplements guide is the place to begin. It covers melatonin, L-theanine, glycine, valerian and ashwagandha, with the evidence and the risks for each. Only after magnesium? Go straight to types of magnesium compared. L-theanine, which people take for evening tension or alongside their morning coffee, has its own guide: L-theanine benefits and dosage.

One thing UK readers need to know first: melatonin is prescription-only here. Unless your GP has prescribed it, the options you can order are magnesium, glycine and L-theanine.

Magnesium for sleep: which form

Magnesium has more guides in this section than anything else, because each form suits a different person.

• Magnesium glycinate is gentle on the gut and the usual evening choice.
• Magnesium citrate costs less and helps if you’re prone to constipation.
• Magnesium with vitamin B6 means checking the B6 dose. The NHS advises no more than 10 mg of B6 a day from supplements.

Sleep and stress supplements at a glance

Each row links to the guide that covers that goal in detail.

Goal	What’s studied	Dose	Guide
Shifted schedule, jet lag	melatonin	0.5–1 mg	melatonin dosage and sleep supplements
Evening tension	L-theanine	200 mg	L-theanine for sleep
Light, restless sleep	glycine	3 g	glycine for sleep
Low-magnesium diet	magnesium glycinate	100–200 mg	magnesium glycinate
Constipation as well	magnesium citrate	100–200 mg	magnesium citrate
Stress, with caution	ashwagandha	per label, short-term	ashwagandha side effects
Low mood, only with a doctor	5-HTP	not with antidepressants	5-HTP and SSRIs

Ashwagandha and 5-HTP carry real risks, so read their safety sections before you buy. Never combine 5-HTP with antidepressants without your doctor.

Before you buy a sleep supplement

Tick what's true for you. Ticks are saved in this browser only

0 / 6 ticked

• I'm starting with one supplement, not three. Melatonin and magnesium can be taken together, but add them one at a time. That way you know what works and what causes side effects.
• I know melatonin is prescription-only in the UK. Without a prescription, magnesium, glycine and L-theanine are what you can order. iHerb may not ship melatonin to a UK address. Read more
• I've checked the B6 in my magnesium with B6. The NHS advises no more than 10 mg of B6 a day from supplements. Read more
• I'm not on antidepressants if I'm looking at 5-HTP. Never combine the two without your doctor. Read more
• I've read the ashwagandha safety section. The effects on stress are modest, and there are real safety caveats. Read more
• My poor sleep has lasted less than three months, and I don't snore with pauses in breathing. If either isn't true, book a GP appointment. Chronic insomnia is treated with CBT-I, not supplements.

Magnesium glycinate on iHerb

Before you buy anything

These habits cost nothing and work for most people:

• Wake up at the same time every day, weekends included.
• Get bright daylight in the first half of the day, even if it’s a short walk.
• Skip coffee and strong tea after lunch.
• Keep your bedroom dark and cool.
• Put your phone away an hour before bed.

If poor sleep drags on for more than three months, or you snore with pauses in your breathing, see your GP. Chronic insomnia is treated with CBT-I (cognitive behavioural therapy for insomnia), not supplements.

Bottom line: what to choose

Jet lag, shifted schedule

Melatonin 0.5–1 mg

Short-term; prescription-only in the UK

Melatonin on iHerb

Evening tension

L-theanine 200 mg

No drowsiness

L-theanine on iHerb

Low-magnesium diet

Magnesium glycinate

Evening, with food

Glycinate on iHerb

Buttons lead to selections of the right form on iHerb. These are affiliate links; your price doesn't change.

FAQ

Can I take melatonin and magnesium together?

Yes. There are no significant interactions between them, and they’re often taken together in the evening. But start with one, so you know what works and whether either causes side effects.

Can I buy melatonin in the UK?

Only on prescription. In the UK melatonin is a prescription-only medicine, so iHerb may not ship it to a UK address. In the EU the rules differ from country to country.

Which supplements for stress are best studied?

There are small studies on L-theanine (200 mg) and ashwagandha. The effects are modest, and ashwagandha has safety caveats. Magnesium may help if you’re low in it. For ongoing anxiety, see your GP.