Restless Legs at Night: The Iron Question Nobody Asks

It arrives when everything else stops. You get into bed, the day is finally over, and your legs start. Not pain exactly, more an unbearable need to move them, and the only thing that helps is getting up again.

If that is your evening, there is a name for it, a set of diagnostic criteria, and one blood test that is worth asking for by name.

🦵 What restless legs syndrome actually is

Restless legs syndrome, also called Willis-Ekbom disease, is a neurological condition rather than a circulation or muscle problem. It is diagnosed clinically, on what you describe, and the criteria are unusually specific for something so easy to dismiss.

All five of these need to be present:

• An urge to move the legs, usually with an uncomfortable sensation that is hard to describe. People reach for words like crawling, fizzing, pulling, or simply "wrong".

• It starts or worsens at rest, when you are sitting or lying still.

• Movement relieves it, at least while you keep moving.

• It is worse in the evening or at night than during the day.

• It is not better explained by something else, such as leg cramps, positional discomfort or habitual foot tapping.

That last criterion is why this belongs with a clinician rather than a checklist. Several things mimic it.

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🩸 The iron question, and why it gets missed

Here is the part worth knowing before any appointment: iron status is one of the first things clinicians look at when restless legs is raised, and it is checked far less often than it should be.

The complication is that you can be low on the iron that matters here while your full blood count looks unremarkable, because the relevant measure is ferritin, which reflects stores rather than circulating haemoglobin. Guidance in this area also uses a higher threshold than the one printed on most lab reports, so a ferritin level that is technically within the reference range can still be low enough to be worth a conversation when restless legs are present.

So the practical version is this. Ask for your ferritin, and ask for the number rather than the word. "Normal" is not an answer you can do anything with, because the threshold that matters for restless legs is not the same as the threshold for anaemia.

This matters more in this community than in the general population, for a reason that connects to something already covered on this site. If your periods are heavy, iron deficiency is a well-recognised consequence, and it tends to get absorbed into the fatigue you already attribute to your existing diagnosis. It is discussed in more detail in our guide to POTS and your cycle.

What happens with that number afterwards is entirely a clinical decision, and this article does not go there.

💊 The medication question that applies specifically to this audience

Certain medications are recognised as capable of triggering or worsening restless legs. The category that matters most here is the sedating antihistamines, the older generation often taken at night, along with some anti-nausea medicines and certain antidepressants.

Which puts a meaningful number of readers of this site in an awkward position, because daily antihistamines are a common part of managing mast cell symptoms, and the sedating ones are frequently the ones taken in the evening.

To be completely clear: this is not a reason to stop anything. Stopping a medication to test a theory is the one thing not to do, and it is the position this site takes on every medication question. What it is, is a reason to raise it, by name, with the person who prescribed it. Whether anything changes, and what, is their call rather than yours.

Bringing the timing with you helps enormously. If the legs start roughly an hour after an evening dose, that is a specific observation. "I think my medication might be doing something" is not.

🔀 Why it gets mistaken for something you already have

If you live with a chronic condition, a new symptom rarely gets its own investigation. It gets absorbed.

Restless legs is unusually easy to absorb, because several things in this space look similar from the outside:

• Poor sleep you already have. If your nights were already broken, another cause of broken nights hides easily. Our guide to non-restorative sleep covers why hours are not the missing part.

• Fidgeting attributed to dysautonomia. People with orthostatic intolerance often shift and move a great deal, for entirely different reasons.

• Joint discomfort in hypermobility. Legs that ache at the end of the day are common enough that another leg symptom does not stand out.

• Anxiety. An urge to move that arrives at bedtime is very easily read as restlessness of a different kind.

The distinguishing features are the ones in the criteria: the relief from movement, and the clear evening pattern. Those two together are what separate it from general discomfort, and they are worth stating in exactly those terms.

🩺 What to ask for, in order

1. Ferritin, with the number. Not "iron levels", and not "is it normal". The specific figure, written down.

2. A review of what you take in the evening, including anything over the counter. Bring the actual list rather than describing it.

3. Whether anything else could explain it, since kidney function and pregnancy are both recognised contributors and both are simple to check.

4. What the next step is if iron is not the answer. Knowing there is one stops the conversation ending at a shrug, and it belongs to whoever is looking after you.

🌙 What people find helps in the meantime

None of this replaces the conversation above. But these come up consistently, and they cost nothing:

• Moving before bed rather than after it starts. A short walk or stretching in the evening, rather than lying down and waiting.

• Keeping the evening consistent. Restless legs follows a daily rhythm, so an erratic bedtime works against you.

• Noticing caffeine and alcohol timing, both frequently reported as making it worse, and both easy to test on yourself over a fortnight.

• Not lying there. Getting up and moving until it settles is not a failure of sleep hygiene, it is the one thing that reliably provides relief.

⚠️ One thing not to do: do not start iron supplements on your own. Iron is not harmless in excess, some people accumulate it, and taking it before the test makes the test uninterpretable. The blood draw comes first.

❓ Frequently asked questions

📚 Sources & further reading

The information in this article is drawn from the following sources. We encourage you to explore them, and to have suspected restless legs syndrome assessed by a qualified clinician.

• NHS: Restless legs syndrome

• National Institute of Neurological Disorders and Stroke: Restless Legs Syndrome

• Cleveland Clinic: Restless Legs Syndrome (Willis-Ekbom Disease)