Sleep Supplements: What Our GP Recommends and What to Avoid

Sleep supplements come up in my consultations constantly, and they’re one of the easiest things to spend money on without much idea of what you’re buying. A search throws up magnesium, valerian, CBD, lavender and ashwagandha, often blended together in products that don’t tell you how much of anything you’re getting.

My aim here is to go through them honestly, which means being as clear about where the evidence is thin as about where it holds up. Some of these are reasonable things to try. Some carry real risks alongside other medications, and there are a few to avoid if you’re pregnant too.

For persistent insomnia, the NHS points to cognitive behavioural therapy for insomnia as the first-line treatment, and that’s where I’d start too. A supplement is worth considering around that rather than instead of it.

Melatonin has some of the strongest evidence, particularly for sleep problems involving our internal body clock, although it’s a prescription-only medicine in the UK.

For supplements such as magnesium, valerian, lavender, CBD and ashwagandha, the evidence is less conclusive. Some studies suggest potential benefits, but more research is needed.

Thin evidence cuts the other way, too, though. It also means nobody can promise you a supplement will work, which is worth holding onto when a product makes confident claims on the label.

Each of these comes up regularly, so here’s what the research says and what’s worth knowing about safety.

Magnesium

Magnesium is essential for normal nerve and muscle function, and some small studies suggest it may improve sleep quality, particularly in people with low magnesium levels. However, the overall evidence remains mixed, and we don’t yet have strong evidence that taking magnesium improves sleep in otherwise healthy people.

Magnesium is generally well tolerated at appropriate doses, although it can cause digestive side effects, particularly diarrhoea. It’s also important to check with a healthcare professional before taking magnesium supplements if you have kidney disease.

If someone wants to try magnesium, I’d suggest a structured trial of up to three months, keeping a sleep diary to see whether it’s making a meaningful difference. If there’s no noticeable benefit, there’s little reason to continue taking it.

Valerian

Valerian is a traditional herbal remedy used to promote relaxation and sleep. Some studies suggest potential benefits, but the evidence is inconsistent.

Valerian can cause headaches and dizziness and may interact with sedating medications. It’s best avoided during pregnancy and breastfeeding.

CBD

There’s growing interest in CBD for sleep, particularly where stress or anxiety may be contributing to sleep difficulties. However, the evidence that CBD itself improves sleep remains limited and inconsistent.

CBD can interact with medications, including some antidepressants, anticoagulants and epilepsy treatments, and may affect liver function. The quality and actual contents of over-the-counter products can also vary considerably, and it should be avoided during pregnancy and breastfeeding.

Lavender

Some studies suggest lavender aromatherapy may promote relaxation and improve perceived sleep quality.

For most adults, using lavender scent as part of a bedtime routine is relatively low risk, although essential oils can cause irritation and shouldn’t be swallowed.

Ashwagandha

Some small studies suggest ashwagandha may modestly improve sleep, particularly in people experiencing stress, but the studies are generally short, and we don’t have good evidence about long-term safety.

There are important safety concerns, including rare reports of liver injury, potential effects on thyroid function and interactions with certain medications. It should be avoided during pregnancy and breastfeeding.

Over-the-counter antihistamines

Sedating antihistamines can provide short-term relief from occasional sleeplessness, but they’re not recommended for regular or prolonged use.

Antihistamines can cause next-day drowsiness and other side effects, particularly in older adults. It’s worth checking the ingredients, as some Nytol products contain herbal remedies rather than antihistamines. These medicines can also cause dry mouth, constipation and urinary difficulties, and some people develop tolerance to their sedating effects. They should only be used for short periods and aren’t a substitute for addressing the underlying cause of insomnia.

Melatonin is a hormone naturally produced by the body that helps regulate our internal body clock. It can be helpful for certain sleep problems, particularly those involving sleep timing, and may also be useful for managing jet lag. However, the timing and dose are important, and it’s not necessarily suitable for everyone.

Melatonin is a prescription-only medicine in the UK. Although it can be useful for certain sleep problems, particularly those involving our internal body clock, it isn’t a general solution for insomnia. The timing and dose matter, and taking it at the wrong time can potentially disrupt sleep patterns further. I’d recommend discussing it with a healthcare professional rather than buying it from unregulated online sources, where the dose and quality may be unreliable.

Caution is worth applying to products containing multiple ingredients, unclear dosages or those purchased from unregulated sellers. Certain supplements are unsuitable for people with particular medical conditions or those taking specific medications.

The first thing I’d encourage people to do is check whether the supplement is appropriate for them. That means looking at the ingredients, the dose, the quality of the product and any potential interactions with medications they’re already taking. Existing health conditions matter here, especially kidney or liver disease.

If you do decide to try something, introduce one product at a time, keep track of the effects and stop if you experience concerning side effects.

Feeling tired isn’t necessarily the same thing as having a sleep problem, and this is a really important distinction. Someone might be getting eight hours of sleep but still feel exhausted because of an underlying medical condition.

Iron-deficiency anaemia, thyroid disorders, diabetes, depression and sleep apnoea are just some of the conditions that can cause persistent fatigue.

Hormonal changes, including perimenopause and menopause, can also have a significant impact on sleep and energy levels.

Sometimes the problem isn’t the quantity of sleep but its quality. Someone with obstructive sleep apnoea may spend eight hours in bed, but experience repeated interruptions to their breathing that prevent restorative sleep.

If you’re consistently tired despite allowing yourself enough time to sleep, or if the fatigue is affecting everyday life, I’d encourage you to see your GP rather than continuing to experiment with supplements.

Lavender raises a point that applies well beyond lavender itself.

A warm bath, a particular book or a set order of doing things can all build the same routine that you learn to associate with sleepiness, and none of them involve taking anything at all.