What Causes Restless Legs? Iron, Pregnancy, Medicines and More
Restless legs syndrome is common, and it is often brushed off as just poor sleep. Yet the question of what causes restless legs matters, because some of the causes are easy to check and fix. This guide walks through the main ones, what to ask your doctor, and what you can do in the meantime.
Low iron is the first thing to check
The brain uses iron to make dopamine, a chemical messenger involved in movement. When iron stores run low, restless legs becomes more likely, even if you are not anaemic. A standard blood count can look normal while ferritin, the measure of stored iron, is low. So ask your doctor for iron studies including ferritin.
Heavy periods, blood donation, pregnancy, a mostly plant-based diet and some digestive conditions all lower iron stores. If any of those apply to you, mention it.
However, do not start iron tablets on your own. Too much iron is harmful, and some people store it too readily. Test first, then take whatever dose your doctor recommends for as long as they recommend it.
Pregnancy
Pregnancy is one of the clearest answers to what causes restless legs, especially in the last three months. Iron and folate demands rise sharply, and sleep is already disrupted. For most women it settles within weeks of giving birth. Meanwhile, many medicines are off the table, so the non-drug measures below and an iron check with your midwife or doctor matter even more.
Medicines that can aggravate it
Several common medicine groups can bring restless legs on or make it worse. These include some antidepressants, sedating antihistamines found in cold, allergy and sleep products, and some anti-nausea medicines. If your restless legs started or worsened after a new medicine, tell your doctor or pharmacist. Do not stop a prescribed medicine on your own.
Other health conditions
- Kidney disease, particularly in people on dialysis.
- Nerve damage in the feet (peripheral neuropathy), which can feel similar and often overlaps.
- Thyroid problems and diabetes, which your doctor can check with a blood test.
- Poor sleep itself. Insomnia, sleep apnoea and shift work all make restless legs worse, and restless legs worsens sleep in return.
What causes restless legs to flare on a given night
Even when the underlying cause stays the same, some nights are much worse than others. Knowing what causes restless legs to flare lets you plan around it. The usual triggers are:
- Caffeine after midday, including tea, cola, energy drinks and chocolate.
- Alcohol in the evening, even a glass or two.
- Long periods of sitting, such as flights, drives and long meetings.
- Being overtired or short of sleep the night before.
- Stress and a busy, wound-up mind at bedtime.
- A heavy late dinner, or going to bed hungry.
A two-week diary usually shows which of these matter for you. Most people find two or three that count, and the rest make little difference.
Family history
Restless legs often runs in families, particularly when it starts before middle age. In those cases there may be no other cause to find. Even so, it is still worth checking iron, because low stores can make an inherited tendency worse.
What traditional practice adds
Chinese medicine looks at what causes restless legs from a different angle. It describes three common patterns. Depletion comes first, where the blood no longer nourishes the muscles and sinews, often after pregnancy, heavy periods or illness. Next is heat at night, with burning feet and a racing mind. Finally there is sluggish circulation, with legs that feel heavy, achy and cold. Interestingly, the depletion pattern lines up closely with low iron.
For the depletion pattern, traditional diet favours warm, nourishing foods. Examples include slow-cooked soups and stews, eggs, lean red meat, dark leafy greens, beetroot, black sesame, red dates and goji berries. Pair plant sources of iron with vitamin C, such as capsicum or citrus, to help absorption, and keep tea and coffee away from meals.
What you can do now
- Ask your doctor for iron studies including ferritin.
- Write down every medicine and supplement you take, and review it with your pharmacist.
- Cut back caffeine, alcohol and nicotine, especially after midday.
- Walk daily, and stretch and massage your calves before bed.
- Keep regular sleep hours and a simple symptom diary for two weeks.
For an evening routine, see our guide to restless legs at night. If you would like help alongside your doctor’s care, read about acupuncture for restless legs in Adelaide.
When to see a doctor
See your doctor if restless legs is regular, if it started after a new medicine, or if you are pregnant. Get same-day help for one swollen, hot or painful leg, for leg weakness, or for numbness that is spreading. The healthdirect page on restless legs syndrome has more background.
Frequently asked questions
What causes restless legs most often?
Often no single cause is found, and it runs in families. Of the causes that can be checked, low iron stores are the most common and the most fixable.
Can I take iron tablets for restless legs?
Only after a blood test. Too much iron is harmful, so let your doctor decide whether you need it and how much.
Does restless legs go away after pregnancy?
For most women it settles within a few weeks of the birth. If it does not, ask your doctor to check your iron again.