If you can't get to sleep, "insomnia" is the obvious label. For a substantial group of people it's the wrong one, and the treatments that follow from it don't work — because the thing keeping them awake isn't a racing mind. It's their legs.
This one is worth getting right, because the two conditions have almost nothing in common in how they're managed. Insomnia is treated with behavioural therapy and sleep timing. Restless legs is, first of all, a blood test.
The features that define it
Restless legs syndrome — also called Willis-Ekbom disease — is a clinical diagnosis, made on the history rather than on a test. Four features have to be present together:
1. An urge to move the legs, usually with an uncomfortable sensation. People describe it as crawling, fizzing, pulling, creeping, or "like I need to stretch but stretching doesn't finish it." It is notoriously hard to put into words, which is part of why it goes unreported. Frequently it isn't described as painful — just intolerable.
2. It starts or worsens at rest — sitting or lying down. Long car journeys, cinemas and flights are the classic provocations.
3. It is relieved by movement, at least while you keep moving. Walking, stretching, pacing, rubbing the legs.
4. It's worse in the evening and at night than during the day. This is a genuine circadian pattern rather than simply the effect of sitting still in the evening.
And a fifth criterion that matters more than it looks: the symptoms aren't solely explained by something else. Leg cramps, positional discomfort, habitual foot tapping, arthritis, muscle pain, leg swelling and venous problems can all produce restless legs and none of them are this condition. That's part of why the diagnosis belongs with a clinician rather than with a checklist.
The third feature is the giveaway
Insomnia does not improve when you walk around. If getting up and moving your legs settles the feeling, and sitting back down brings it back, that is not insomnia.
The same test separates it from general restlessness and from anxiety, neither of which usually has that clean relief-on-movement pattern. It also separates it from ordinary discomfort, which doesn't return the moment you stop moving.
If you're not sure, the useful thing to do is notice what you already do about it. People with restless legs have almost always worked out on their own that getting up helps. They just haven't connected that to the sleep problem they went to the doctor about.
The related thing your partner may have noticed
Periodic limb movements during sleep are repetitive leg jerks or twitches occurring through the night. They are common in people with restless legs, and they happen while you're asleep — so the person who reports them is usually the one sharing the bed.
That matters for two reasons. It's corroborating information worth bringing to an appointment. And when it's frequent enough to fragment sleep, it becomes its own diagnosis — periodic limb movement disorder — which, unlike restless legs, does need a sleep study to establish.
Those repeated arousals have a further consequence worth knowing: they are one of the things that can trigger sleepwalking and night terrors in someone predisposed to them. If there are episodes in the household as well as restless legs, the two may be connected — and treating the limb movements can settle both.
Why it gets mislabelled
The complaint that reaches the doctor is "I can't sleep." The leg sensation is hard to describe, feels trivial to mention, and often isn't volunteered at all. Meanwhile the symptoms are worse in the evening, so by the time anyone is sitting in a daytime appointment there is nothing to feel and nothing to show.
So people end up working through sleep hygiene, then melatonin, then something stronger, for a problem none of those address. If the sleep advice you've been given hasn't touched it, that's information.
Who gets it
Several groups are notably more affected, and recognising yourself in one of them is a reason to raise it:
- People with low iron stores — the single most important association, and the reason this article ends where it does.
- Pregnancy, particularly the third trimester. It is common, often resolves after delivery, and iron status is especially relevant.
- Kidney disease, particularly in people on dialysis, where it is very common.
- Peripheral neuropathy, including diabetic neuropathy.
- A family history — there is a strong genetic component, and many people find on asking that a parent had it without ever naming it.
- Increasing age, and it is more common in women.
What makes it worse — including things you may be taking
A number of widely used medications can provoke or worsen restless legs, and this is one of the most productive things to review:
- Antidepressants — SSRIs and SNRIs, and mirtazapine in particular
- Sedating antihistamines — including diphenhydramine, which is in many over-the-counter sleep aids, so someone can be taking a sleep product that worsens the thing keeping them awake
- Anti-nausea medications that block dopamine, such as metoclopramide and prochlorperazine
- Some antipsychotics
Do not stop a prescribed medication on the strength of this list. Bring the full list — prescription, over-the-counter and supplements — to a pharmacist or prescriber and ask the question there. Alternatives often exist, and abruptly stopping an antidepressant causes its own problems.
Non-drug aggravators worth testing on yourself: caffeine, alcohol and nicotine. All three are commonly implicated, all three are free to reduce, and alcohol in particular is a bad trade here — it can worsen symptoms in the second half of the night.
What actually helps
First, a blood test — not a supplement. Iron status is central to restless legs, and the threshold that matters is higher than the one labs use to flag a result as low. This is the highest-value action available and it is routinely skipped. The specific tests to ask for, and the numbers that apply, are here.
Second, the medication review above.
Third, be aware the treatment landscape changed, and most advice online hasn't caught up. Dopamine agonists — pramipexole, ropinirole, levodopa — were first-line for years. Current guidance recommends against their routine use, because of augmentation: the drug gradually making symptoms worse over months to years, starting earlier in the day and spreading beyond the legs. The alpha-2-delta ligands, gabapentin enacarbil and pregabalin among them, now carry conditional recommendations instead. If you are on a dopamine agonist and your symptoms have crept earlier or spread, that is a specific conversation to have at a review — and not one to act on alone, since stopping abruptly can cause a rebound.
And if it turns out to be insomnia after all — which for many people reading this it will be — CBT-I has better evidence behind it than anything you can buy. Two further possibilities if the legs aren't the issue: if you sleep a full night and wake unrefreshed, screen for sleep apnea; and if you fall asleep during the day regardless of how much you slept, that's a different condition with a notoriously slow diagnosis.
Our honest position
We sell sleep supplements and this is largely not a sleep-supplement problem.
Magnesium is widely recommended for restless legs online, and the trial evidence for it is thin — a small number of small studies, no strong recommendation from any guideline. We stock magnesium and we are still not going to imply otherwise. Nothing in our range treats restless legs syndrome.
If this is what you have, the useful next step is a ferritin and transferrin saturation test, and the reason we're writing this at all is that a lot of people never get that far.
This article is not medical advice. Restless legs syndrome is a clinical diagnosis made by a doctor, and nothing here should be used to start, stop or change a medication.