Causes of Restless Legs During Sleep | Iron to Genetics • Sleep & Pulmonology Clinic in Riyadh

The causes of restless legs during sleep fall into two types: primary causes linked to genes, and secondary causes resulting from another medical condition, the best known of which is low iron stores.

Telling the two apart is the most important step in treatment, because the second type is usually correctable once its cause is addressed.

The reassuring news is that this disorder has a treatment, and the response rate is high in most patients.

What Is Restless Legs Syndrome?

A neurological disorder that causes an urgent need to move the legs, accompanied by an uncomfortable sensation that appears during periods of rest, particularly in the evening or on lying down to sleep, and improves temporarily with movement.

Patients describe this sensation in varied ways:

A feeling of things crawling on the legs.
Numbness or a dull sensation in the legs.
Vague aches and pains that are hard to describe precisely.
A strong, persistent urge to move the legs at bedtime.

The four criteria that distinguish the condition from others:

An urgent need to move the legs accompanied by an uncomfortable sensation.
Symptoms intensify during stillness and rest.
They improve temporarily with movement.
They worsen in the evening and at night more than during the day.

The fourth criterion in particular is what separates this condition from ordinary leg pain or numbness caused by other reasons.

Diagnosing this condition does not rest on a single test, but on a careful clinical assessment that starts with a sleep disorders consultation.

What Are the Causes of Restless Legs During Sleep?

1. Genetics and the Hereditary Factor

In many cases the causes of this syndrome are not precisely known, but they are believed to be linked to genes and can be inherited, since most people with it turn out to have a family history of the condition.

This explains why symptoms in some patients start at a relatively early age with no clear medical cause.

2. Iron Deficiency and Low Iron Stores

One of the best known secondary causes and the most correctable.

The most important point here: even when iron deficiency does not cause anemia, it may cause or worsen restless legs syndrome. In other words, a haemoglobin test alone may come back normal while iron stores (ferritin) are low, and this is a common reason for a missed diagnosis.

Those in whom iron deficiency should be suspected include people with a history of stomach or intestinal bleeding, women with heavy menstrual periods, and anyone noticing repeated blood loss.

3. Accompanying Chronic Diseases

Kidney failure: leads to iron deficiency usually accompanied by anemia, because iron stores fall when kidney function declines.
Diabetes: through its effect on the peripheral nerves.
Parkinson's disease: because of its link to dopamine pathways in the brain.
Obesity.
Peripheral neuropathy: damage affecting the nerves of the hands and feet, sometimes traced to a chronic illness such as diabetes.
Narrowing and hardening of the arteries of the lower limbs.

4. Medications

Some common medications may cause or worsen the condition, most notably antihistamines and antidepressants, along with some cold medicines and antipsychotics.

This is an important practical point: a patient taking a daily antihistamine for a seasonal allergy may themselves be the source of their night symptoms without connecting the two.

5. Pregnancy

Many women experience the condition, particularly in the later months of pregnancy, and it usually disappears once the pregnancy ends.

6. Other Factors

Alcohol, vitamin D deficiency, low physical activity, and sleep difficulties arising from various causes.

Why Do Symptoms Worsen Specifically in the Evening?

This question occupies many patients, and answering it is tied to understanding the condition itself.

Dopamine activity in the brain, the neurotransmitter responsible for regulating movement, follows a daily rhythm that reaches its lowest levels in the evening and night hours. As it falls, symptoms increase.

Added to this is the stillness factor: the condition appears at rest, and evening is the longest period of stillness in the day. This is why patients also complain of symptoms while watching television or on long car journeys, not only at bedtime.

This close link with sleep is what places the condition among sleep disorders even though its symptoms are in the legs.

The Difference Between Restless Legs and Periodic Limb Movement

The two conditions are often confused, and the difference is fundamental:

Restless legs: a conscious sensation the patient feels and can describe, and which prevents them from sleeping.
Periodic limb movement disorder: repeated involuntary movements during sleep that the patient usually does not feel; the partner notices them instead. They may cause repeated awakenings without the patient knowing why.

The two can occur together in one patient. The practical difference is that the second cannot be diagnosed by description. It needs objective recording of limb movements during sleep, which is what the advanced sleep study with brain wave recording provides, since leg movements are among its recorded indicators.

Is Restless Legs Dangerous?

The condition in itself does not usually indicate a serious medical problem, but studies have linked it to other conditions that deserve attention.

One study reported an 88% higher rate of death during the follow-up period among people with restless legs, and the researchers attributed this association to the disorder's effect on sleep quality.

Precise interpretation matters here: this type of study shows an association between restless legs and these diseases, but it does not mean restless legs causes them. Chronic sleep deprivation may be the mediator, or both conditions may result from a shared third factor.

The practical conclusion is not alarm but not dismissing it either: the disorder has a treatment, and the response rate is high.

How Is Restless Legs Diagnosed?

The causes of restless legs during sleep cannot be identified through a single test, so diagnosis rests on four elements:

The patient's description of their symptoms: the patient's answers to the doctor's questions play a core role, as they are compared against the four criteria above.
Reviewing the family medical history: to determine whether a hereditary factor is present.
Reviewing current medications: to rule out a medication cause.
Blood tests: most importantly iron stores (ferritin), along with kidney function, thyroid function, and vitamin D, to rule out secondary causes.

A sleep study may be requested in certain cases: when accompanying periodic limb movement disorder is suspected, or when there is severe insomnia or daytime sleepiness not explained by the symptoms alone.

Assessment may also need to rule out accompanying sleep disorders, and you can read more about sleep apnea treatment and its diagnostic steps.

The advantage at Subat Clinics is that sleep tests are carried out at the patient's home, so they sleep in their own bed at their usual time, which gives a picture closer to their actual reality.

What Are the Treatment Options?

Treatment depends on the cause and the severity, and it always starts by addressing the secondary cause if one is present.

1. Correcting Iron Deficiency

The first step if iron stores are low, and it may on its own be enough for symptoms to disappear in many cases.

2. Reviewing Medications

If a medication is the cause, adjusting or replacing it in coordination with the prescribing physician may be enough. No medication should be stopped on your own.

3. Treating the Accompanying Condition

Such as controlling diabetes or managing kidney impairment.

4. Lifestyle Adjustments

Regular physical activity, leg massage, warm baths, and staying away from nicotine and caffeine, particularly in the evening.

5. Medication

This consists of tablets dispensed according to each patient's needs, and the response to treatment is good in most people affected. It includes dopamine-related compounds in certain cases, which are dispensed by prescription and need close follow-up.

If insomnia persists despite the leg symptoms being controlled, there may be an independent sleep disorder needing separate assessment, and cognitive behavioural therapy for insomnia is useful here.

When Should You See a Doctor?

See a specialist if:

The symptoms are accompanied by daytime sleepiness affecting your work or your driving.
The symptoms prevent you from sleeping or wake you at night regularly.
They have continued for more than three months.
Their severity has gradually increased over time.
They have spread to the arms or other parts of the body.
They appeared after starting a new medication.

For women specifically: if symptoms appear alongside heavy menstrual periods, iron stores deserve early testing.

Initial assessment or follow-up can be arranged through a remote sleep disorders consultation for those living outside Riyadh.

Why Subat Clinics?

At Subat Clinics in Riyadh, the patient gets:

An assessment that looks for the cause rather than the symptom, because a large share of cases are caused by iron deficiency or a medication, and both are correctable.
A Saudi team specialized in pulmonary medicine and sleep disorders.
Fully home-based sleep tests, including the advanced study that records limb movements, with no overnight lab stay.
Results within 3 working days, read by the consultant themselves.

You can browse the available consultations to choose what suits your case.

Book Your Assessment

The causes of restless legs during sleep may come down to a simple shortfall in iron stores or a medication that can be adjusted. A proper assessment therefore saves many nights of insomnia and shifting your legs in search of a comfortable position.

📍 Othman Bin Affan Road, Al Taawun District, Riyadh 12477
🕔 Sunday to Wednesday, 5 – 9 PM
📞 0112011100
💬 WhatsApp: 0505999713

Book your appointment now

Sources:

This content is for health awareness purposes and does not replace a personal medical consultation. Do not start or stop any medication or supplement based on it without consulting your doctor.

Medically reviewed by:
Dr. Ahmed Alruhaimi — Consultant in Pulmonary Medicine and Sleep Medicine, Subat Clinics.
Last reviewed: August 2026.

Frequently Asked Questions

Is restless legs a psychological illness?
No. It is a neurological disorder linked to dopamine pathways, not a psychological condition. But the chronic sleep deprivation it causes may produce tension and mood swings, so the condition is sometimes misread as anxiety.

Can it affect the arms?
Yes, though less commonly. The sensations usually occur on both sides of the body, and they may affect the arms in less frequent cases.

Do the symptoms disappear permanently?
If the cause is secondary, such as iron deficiency, a medication, or pregnancy, symptoms usually disappear once the cause is treated. Primary hereditary cases are managed with long-term treatment, noting that symptoms may vary in severity and disappear for periods before returning.

Is taking an iron supplement on my own a suitable solution?
No. Increasing iron without an actual deficiency may cause harm, and the dose and duration are set after measuring iron stores. Start with the test, not the supplement.

Does exercise help or worsen symptoms?
Regular moderate physical activity helps, while strenuous effort close to bedtime may worsen symptoms in some patients.

My son complains of the same symptoms — is it inherited?
A hereditary factor exists, and most people affected have a family history. But symptoms in children need specialized assessment by a pediatrician to rule out other causes such as growing pains.

Could it be the only cause of my insomnia?
Possibly, but many patients have an accompanying sleep disorder, such as sleep apnea or chronic insomnia, which is why assessment usually includes ruling out other conditions.