Restless Legs at Night: Causes, Treatments, and What to Do

TL;DR

• Restless legs syndrome is a neurological condition characterised by an urge to move the legs, typically worse at rest and in the evening, and relieved by movement.
• The primary mechanism involves dopamine signalling in the brain. Iron deficiency, which affects dopamine production, is one of the most important and modifiable risk factors.
• Many common medications can cause or worsen RLS, including SSRIs and antihistamines. A medication review is worth doing if symptoms started or worsened around a new prescription.
• Effective prescription treatments exist. Alpha-2-delta ligands are now preferred over dopamine agonists due to the risk of symptom worsening with long-term dopamine agonist use.
• RLS shares some features with REM behavior disorder, a separate condition with a different mechanism and different clinical significance. Both warrant a sleep specialist or neurologist assessment.

Lying down to sleep and immediately feeling an overwhelming need to move your legs is one of the more frustrating sleep experiences. The urge passes the moment you get up, then returns the moment you lie back down. Restless legs syndrome is real, measurable, and treatable. Understanding what causes it is the starting point for finding what helps.

What Restless Legs Syndrome Is

RLS is a neurological sensorimotor condition defined by four diagnostic criteria: an urge to move the legs (sometimes accompanied by uncomfortable sensations), the urge occurs or worsens during rest or inactivity, it is at least partially relieved by movement, and it is worse in the evening or night compared to the morning. All four criteria must be present for a diagnosis.

The sensations people describe vary. Some report crawling, creeping, pulling, or itching feelings deep in the calves. Others simply feel a compelling urge to move with no specific sensation. The defining feature is the interaction between rest and movement: rest brings the urge, movement relieves it.

The Dopamine Mechanism

The central mechanism in RLS involves dopamine signalling. The dopaminergic pathways that help regulate movement are disrupted in RLS, producing the sensorimotor symptoms. This is why dopamine-related medications were historically the first-line treatments.

Iron is directly involved because iron is a cofactor in dopamine production. The substantia nigra, a brain region central to movement regulation, has particularly high iron requirements. Studies have found that iron deficiency in this region, even when serum ferritin levels appear borderline normal in blood tests, is associated with RLS symptoms. Ferritin levels below 50 to 75 micrograms per litre are considered insufficient for optimal dopamine function in people with RLS, even though this falls within the broad standard range.

Iron Deficiency as a Modifiable Risk Factor

Iron deficiency is one of the most clinically important and modifiable contributors to RLS. In some people, correcting iron deficiency produces significant or complete relief of symptoms. This matters because it means a blood test and supplementation, rather than a lifelong prescription, may be sufficient.

If you have RLS, asking your doctor to check ferritin (not just haemoglobin or standard iron panels) is worthwhile. The target ferritin for symptom reduction in RLS tends to be higher than the standard laboratory lower limit of normal. Supplementation typically needs to continue for several months to achieve meaningful change.

Genetics and Secondary Causes

RLS has a strong genetic component. First-degree relatives of people with RLS have approximately three to five times the risk of developing it themselves. Multiple genome-wide association studies have identified variants associated with the condition.

Secondary RLS, meaning RLS caused by another underlying condition or substance, is common. Medications are a major cause. SSRIs, SNRIs, antipsychotics, antihistamines (including over-the-counter sleep aids and allergy medications), and certain antiemetics can cause or significantly worsen RLS. If symptoms began or worsened after starting a new medication, a medication review with the prescribing doctor is a reasonable first step.

Other secondary causes include pregnancy, kidney disease, and peripheral neuropathy. Caffeine and alcohol are associated with worsening symptoms in some people.

Lifestyle and Non-Pharmaceutical Approaches

For mild RLS, several non-pharmaceutical approaches have some evidence: moderate exercise during the day (though vigorous exercise close to bedtime may worsen symptoms), leg massage, warm baths before bed, and maintaining a consistent sleep schedule. Reducing caffeine and alcohol can help in sensitive individuals.

These approaches are generally insufficient for moderate to severe RLS but can be a useful adjunct to other treatments.

Medications for RLS

When lifestyle measures are insufficient, prescription treatment is usually needed for moderate to severe RLS.

Alpha-2-delta ligands (pregabalin and gabapentin) are now the recommended first-line medications by most movement disorder and sleep medicine specialists. They target a different pathway than dopamine agonists and carry lower risk of the main long-term complication.

Dopamine agonists (pramipexole and ropinirole) were historically the standard first-line treatment. They are effective, but long-term use carries a significant risk of augmentation, a paradoxical worsening of RLS symptoms that spreads earlier in the day, intensifies, and can involve the arms and body. Augmentation is now recognised as a serious limitation of long-term dopamine agonist therapy, which is why guidelines have shifted toward alpha-2-delta ligands.

Opioids are used in refractory cases. Iron infusion is increasingly used, particularly when serum ferritin is low or low-normal, and has strong evidence in several clinical trials.

How RLS Affects Sleep

RLS directly delays sleep onset. Lying down triggers the urge, which makes staying still to fall asleep difficult. Many people with RLS end up shifting to very late sleep times because the symptoms are worst in the early evening and often ease by late night.

Beyond onset, people with RLS also have a high rate of periodic limb movements of sleep, repetitive leg jerks during sleep that can cause arousals and fragment sleep architecture. These are often only identified through sleep study.

REM Behavior Disorder: A Related Condition Worth Knowing About

RLS and REM behavior disorder are separate conditions with different mechanisms and different clinical implications. They are worth distinguishing because they can sometimes be confused, and because RBD carries a significance that warrants specific attention.

What RBD Is

REM behavior disorder is a condition in which the normal muscle paralysis that occurs during REM sleep fails. During healthy REM sleep, the brain sends signals that create temporary muscle atonia, preventing people from physically acting out their dreams. In RBD, this atonia mechanism does not work properly. People physically act out dream content during REM sleep, often involving movements like punching, kicking, shouting, or jumping out of bed.

Critically, people with RBD are usually unaware of these episodes. The condition is often first noticed by a bed partner who observes the movements and vocalisations. Episodes can range from mild arm movements to vigorous and occasionally injurious activity.

Diagnosis requires polysomnography, a sleep study that measures muscle activity during sleep. The finding of sustained muscle tone during REM sleep, when it should be absent, confirms the diagnosis.

The Neurodegenerative Connection

The clinical significance of RBD goes well beyond sleep disruption. RBD is strongly associated with the alpha-synuclein group of neurodegenerative diseases, which includes Parkinson's disease, Lewy body dementia, and multiple system atrophy.

A landmark multicentre study by Postuma and colleagues published in Brain in 2019 followed 1,280 people with confirmed idiopathic RBD across 24 centres for an average of 4.6 years (range 1 to 19 years). The study found a conversion rate of 6.3% per year to a defined neurodegenerative disease. At 12-year follow-up, 73.5% of participants had converted to Parkinson's disease, Lewy body dementia, or multiple system atrophy.

This does not mean that everyone with RBD will develop one of these conditions. Research into neuroprotective interventions for people with RBD is active, and the field is moving. What it means is that a confirmed diagnosis of idiopathic RBD represents a meaningful signal that warrants specialist involvement and, in many cases, enrolment in research or monitoring programs.

Who Should Know About This

If a bed partner or family member has noticed episodes of shouting, talking, punching, kicking, or thrashing during sleep, particularly episodes that appear to involve acting out dream content, this deserves medical assessment. A GP can refer to a sleep specialist or neurologist for evaluation and, if indicated, polysomnography.

For people with confirmed RBD, management involves safety measures to protect against injury during episodes, and specialist oversight. A neurologist, ideally one with movement disorder expertise, is the appropriate specialist for ongoing management. The field is developing, and research centres are actively recruiting participants for neuroprotective trials.

The framing to hold onto is this: RBD is significant information, not a sentence. Many people live for years or decades without conversion to a neurodegenerative condition. Knowing about it early, with appropriate specialist involvement, puts people in the best position to participate in research and to be monitored appropriately.

What This Means for Your Sleep

RLS and RBD are both neurological conditions that affect sleep but through completely different mechanisms. RLS disrupts sleep onset through sensorimotor symptoms tied to dopamine and iron. RBD disrupts sleep by allowing physical movement during dream states, and carries a separate clinical significance related to neurodegeneration.

For RLS, the key practical steps are checking ferritin, reviewing medications, and speaking with a doctor about prescription options if symptoms are moderate to severe. For RBD, or if RBD is suspected, a sleep specialist or neurologist assessment is the appropriate next step.

Both conditions respond to proper evaluation and management. Getting the right assessment is the most important thing you can do.

For more on how sleep disruption affects daytime function, see our article on sleep deprivation symptoms. For practical approaches to improving sleep onset, see how to fall asleep fast.

Frequently Asked Questions

Is restless legs syndrome a real medical condition?

Yes. RLS is recognised as a neurological sensorimotor disorder with defined diagnostic criteria, identified biological mechanisms, genetic associations, and established treatments. The condition has been studied extensively. The fact that symptoms are largely subjective and intermittent has historically caused some people, including some clinicians, to underestimate it. The research is clear that RLS causes real sleep disruption and responds to targeted treatment.

Can iron supplements fix restless legs?

For some people, yes. Iron deficiency, particularly low ferritin, is one of the most modifiable contributors to RLS. Studies have shown that correcting iron deficiency can significantly reduce or eliminate symptoms in some patients. The threshold for iron sufficiency in RLS is higher than the general population threshold. A ferritin level below 50 to 75 micrograms per litre is considered insufficient for people with RLS even if a standard lab report marks it as normal. If you have RLS and have not had ferritin specifically tested, it is worth asking for.

What is the difference between restless legs and REM behavior disorder?

Restless legs syndrome causes an urge to move the legs while awake and at rest, particularly in the evenings. The mechanism involves dopamine signalling. REM behavior disorder is a condition that occurs during sleep, in which the normal muscle paralysis of REM sleep fails and people physically act out dream content. The mechanism involves the brainstem circuits responsible for sleep-related muscle atonia. The two conditions sometimes coexist and can be confused, but they are different in mechanism, presentation, and clinical significance. RBD carries a specific association with alpha-synuclein neurodegenerative diseases that RLS does not.

If my partner notices me thrashing or shouting in my sleep, what should I do?

See a GP and ask for a referral to a sleep specialist or neurologist. Acting out dream content during sleep is the hallmark presentation of REM behavior disorder. Diagnosis requires a sleep study (polysomnography) that measures muscle activity during REM sleep. If RBD is confirmed, a neurologist with movement disorder expertise is the appropriate specialist for ongoing management. Early identification matters for safety, for monitoring, and for potential participation in research programs.

Should I be worried if I have been diagnosed with RBD?

A diagnosis of idiopathic RBD warrants specialist involvement and appropriate monitoring. The long-term statistics on conversion to neurodegenerative disease are significant, but the course is variable and research into neuroprotective interventions is active. Many people with RBD live for years without developing additional neurological conditions. What a diagnosis means practically is that specialist oversight, safety measures during sleep, and awareness of the condition are all appropriate. A neurologist with movement disorder expertise is best placed to advise on what monitoring and research involvement makes sense for an individual situation.

This article is for general information only and does not constitute medical advice. RLS and REM behavior disorder are neurological conditions that both benefit from proper medical assessment. If you suspect either condition, speak with your GP about a referral to a sleep specialist or neurologist. For RBD specifically, a neurologist with movement disorder expertise is recommended.