Restless Leg Syndrome — Symptoms, Causes & Treatment | MyMedicPlus

Restless legs syndrome (RLS), also known as Willis-Ekbom disease, is a common neurological sensorimotor disorder characterised by an uncomfortable, irresistible urge to move the legs — typically accompanied by unpleasant sensory symptoms described as creeping, crawling, pulling, itching, or tingling deep within the legs. These sensations characteristically worsen at rest (particularly when sitting or lying down), are worst in the evening and night, and are temporarily relieved by movement. RLS is one of the most common neurological disorders, affecting 5–10% of adults in Western populations, with a significant female predominance and increasing prevalence with age. It is a leading cause of chronic insomnia, with profound effects on sleep quality, daytime alertness, mood, and quality of life. Severity exists on a spectrum from mild and intermittent (manageable without medication) to severe and near-nightly, causing severe sleep deprivation and functional disability. RLS is classified as primary (idiopathic — most common, strongly genetic) or secondary (associated with iron deficiency, pregnancy, renal failure, peripheral neuropathy, or medications). The International Restless Legs Syndrome Study Group (IRLSSG) Severity Scale (0–40) quantifies symptom severity and guides treatment decisions.

Primary (idiopathic) RLS involves dopaminergic pathway dysfunction — specifically, impaired spinal dopamine modulation of sensory and motor pathways. Iron deficiency at the level of the basal ganglia and substantia nigra is fundamental — iron is an essential cofactor for tyrosine hydroxylase (the rate-limiting enzyme in dopamine synthesis), and reduced brain iron impairs dopaminergic function even when peripheral iron indices appear borderline normal. Serum ferritin below 75 mcg/L is associated with worsening RLS and is a treatable target. Genetic basis: primary RLS is strongly hereditary — approximately 50–70% of cases have a positive family history, predominantly autosomal dominant. Genome-wide association studies (GWAS) have identified susceptibility variants in BTBD9, MEIS1, MAP2K5, and PTPRD — genes involved in neuronal development and dopaminergic signalling. Secondary RLS causes include: iron deficiency (any cause — menstruation, GI blood loss, malabsorption, poor dietary intake); pregnancy (affects 20–25% of pregnant women — typically in the third trimester, resolves after delivery; iron and folate deficiency contribute); end-stage renal disease and dialysis (prevalence 25–45% in dialysis patients — the most severe secondary RLS); peripheral neuropathy (diabetic, uraemic, alcohol-related); and medications that exacerbate RLS — dopamine antagonists (antipsychotics, metoclopramide, prochlorperazine), antihistamines (H1 blockers — promethazine, chlorphenamine), SSRIs and mirtazapine (serotonin excess impairs dopaminergic signalling), and tricyclic antidepressants.

RLS is characterised by four essential diagnostic criteria (IRLSSG — International RLS Study Group): (1) an urge to move the legs, usually accompanied or caused by uncomfortable and unpleasant sensations in the legs — described variously as creeping, crawling, pulling, tugging, itching, tingling, burning, or 'fizzing'; (2) the urge to move and unpleasant sensations begin or worsen during periods of rest or inactivity (sitting, lying down); (3) the urge to move and unpleasant sensations are partially or completely relieved by movement (walking, stretching, rubbing) — relief persists only as long as the activity continues; (4) the urge to move and unpleasant sensations are worse in the evening or night than during the day, or only occur in the evening or night. Symptoms predominantly affect the legs but can involve the arms, trunk, and face in severe cases. Periodic limb movements in sleep (PLMS — involuntary, rhythmic flexion of the ankle, knee, and hip during sleep, typically in 20–40 second cycles) are present in 80% of RLS patients and frequently disrupt the sleep of both the patient and their bed partner — detectable on polysomnography. Associated complications: chronic sleep-onset insomnia (the most disabling consequence), excessive daytime sleepiness, impaired concentration and memory, and mood disturbance (depression and anxiety). The condition does not affect sensation on clinical examination — neurological examination is normal in primary RLS (abnormal findings suggest secondary cause).

RLS is a clinical diagnosis based on the four IRLSSG essential criteria — no confirmatory blood test or imaging is required for diagnosis. However, investigations are essential to identify secondary causes and guide treatment. Mandatory blood tests: serum ferritin (the most important test — target above 75 mcg/L; values below 75 mcg/L warrant iron supplementation even if haemoglobin is normal, as brain iron depletion occurs before systemic deficiency); full blood count (anaemia); renal function (eGFR and creatinine — uraemic RLS); thyroid function tests (hypothyroidism association); fasting glucose and HbA1c (diabetic peripheral neuropathy as a secondary cause); and magnesium levels. Polysomnography (PSG — overnight sleep study): indicated when PLMS are causing significant sleep disturbance affecting both partners, when concurrent obstructive sleep apnoea is suspected, or when clinical diagnosis is uncertain. Electrophysiology (nerve conduction studies): indicated if peripheral neuropathy is suspected as the underlying cause. Differentiate from: nocturnal leg cramps (painful, involuntary muscle contractions — no urge to move, no circadian pattern, not relieved by walking); peripheral neuropathy (sensory symptoms — burning, numbness — present throughout the day, not specifically at rest or worse in the evening); vascular insufficiency (claudication — pain with walking, not at rest); and positional discomfort (relieved by repositioning, not by ambulation).

Iron supplementation (first-line for all RLS patients with ferritin below 75 mcg/L): oral ferrous sulfate 325 mg once to three times daily with vitamin C (to enhance absorption) on an empty stomach, or ferrous fumarate/gluconate if sulfate is poorly tolerated; aim for ferritin above 75–100 mcg/L (some guidelines suggest above 300 mcg/L for maximum benefit); takes 3–6 months to show full effect. IV iron (ferric carboxymaltose, iron sucrose) for patients who cannot absorb or tolerate oral iron, or who require rapid correction. Non-pharmacological: identify and stop aggravating medications (antipsychotics, metoclopramide, antihistamines, SSRIs if possible); moderate regular aerobic exercise (30 minutes daily — avoid vigorous evening exercise); leg massage, warm baths or compresses, and mental engagement during symptomatic periods. Dopamine agonists (first-line pharmacotherapy for moderate-severe primary RLS): pramipexole 0.125–0.54 mg nightly, 2–3 hours before usual symptom onset; ropinirole 0.25–4 mg nightly; rotigotine transdermal patch 1–3 mg/24h (particularly useful for early morning symptoms and for those who struggle with oral dosing timing). All are effective in 70–80% of patients. Risk of augmentation with long-term use requires monitoring — use minimum effective dose. Alpha-2-delta calcium channel ligands (preferred over dopamine agonists when augmentation is a concern, or for concurrent insomnia, anxiety, or neuropathic pain): pregabalin 75–300 mg nightly (PHASE 3 trial: non-inferior to pramipexole with lower augmentation rate); gabapentin enacarbil 600–1200 mg nightly; gabapentin 300–2400 mg nightly. Opioids (buprenorphine low-dose, oxycodone extended-release + naloxone — Targinact): for severe, refractory RLS or augmentation — highly effective but limited by addiction potential and MHRA regulations. Switching strategy for augmentation: gradually taper dopamine agonist over weeks to months while initiating pregabalin — temporary worsening is expected during the transition.

Chronic, severe RLS causes significant sleep deprivation — the most burdensome direct complication. Resulting consequences include excessive daytime sleepiness (impairing driving safety and occupational performance), impaired cognitive function (concentration, memory, executive function), mood disturbance (depression and anxiety are comorbid in approximately 20–30% of chronic RLS patients), and quality-of-life impairment comparable to chronic pain conditions. Augmentation is the most important iatrogenic complication of dopamine agonist therapy — a paradoxical worsening of RLS symptoms characterised by earlier onset of symptoms (earlier in the day), increased severity, spread to the arms and trunk, and need for progressively larger doses to achieve control; affects up to 50% of patients on long-term pramipexole or ropinirole. Augmentation requires gradual weaning of the dopamine agonist (with temporary severe symptom worsening expected) and switching to alpha-2-delta ligands or opioids. Some population-based studies suggest that RLS with significant PLMS is independently associated with elevated cardiovascular disease risk through nocturnal arousals and sympathetic blood pressure surges. Pregnancy-related RLS causes severe insomnia and contributes to gestational depression and perinatal complications. Rebound insomnia occurs on abrupt discontinuation of sedative or dopaminergic medications used for RLS.

Maintain adequate iron stores — serum ferritin should be above 75 mcg/L (ideally above 100 mcg/L) for optimal dopaminergic function and RLS symptom control. All women of reproductive age, blood donors, vegans, vegetarians, and patients with GI disorders (coeliac disease, inflammatory bowel disease, previous bariatric surgery) should have ferritin checked annually. Avoid medications known to trigger or worsen RLS: dopamine antagonists (antipsychotics — haloperidol, risperidone, olanzapine, metoclopramide, prochlorperazine — avoid or switch if clinically possible); antihistamines (particularly promethazine and chlorphenamine — use non-sedating alternatives such as cetirizine or loratadine instead); SSRIs and mirtazapine (if antidepressants are needed, bupropion and tramadol have less RLS impact); TCAs; and lithium. Avoid caffeine (coffee, tea, energy drinks, cola) especially after 2 pm. Limit alcohol — especially within 4 hours of bedtime (alcohol disrupts sleep architecture and worsens RLS). Regular moderate aerobic exercise (30 minutes of walking or swimming daily — avoid vigorous exercise within 2 hours of bedtime). Maintain consistent sleep and wake times. In pregnancy: check iron and folate levels; supplement as necessary; moderate physical activity; RLS typically resolves within 4 weeks of delivery. Treat underlying conditions: optimize diabetes control (prevents or limits peripheral neuropathy); dialysis scheduling (nocturnal dialysis reduces RLS in CKD patients); renal transplantation resolves uraemic RLS in most cases.

See your GP if: uncomfortable creeping, crawling, or tingling sensations in your legs that are worse at rest and in the evening are disrupting sleep on three or more nights per week; leg discomfort is severe enough to significantly affect daily functioning, mood, or quality of life; you are pregnant and experiencing new or worsening restless legs symptoms (pregnancy is a common trigger and iron deficiency should be tested); and if any medication you are taking (antidepressants, antipsychotics, antihistamines, metoclopramide) appears to have triggered or worsened your symptoms — do not stop prescribed medications without advice, but mention this to your prescriber. Request an urgent neurology or sleep medicine referral if: symptoms are severe, disabling, and not responding to iron supplementation or lifestyle measures; augmentation has developed on dopamine agonist therapy (symptoms worsening earlier in the day, spreading to the arms, requiring increasing doses) — this requires specialist management with dose reduction or switch to alternative class; and when RLS is associated with other neurological symptoms, significant sleep apnoea, or renal failure. Blood tests your GP should check include serum ferritin, full blood count, renal function, thyroid function, and fasting glucose — these rule out secondary causes.