Restless leg syndrome (RLS) causes an uncomfortable, hard-to-ignore urge to move your legs, typically striking in the evening or at night when you’re sitting or lying down. The sensations feel deep in the muscles rather than on the skin, and moving your legs provides temporary relief. About 80% of people with RLS also experience involuntary leg jerking during sleep, which compounds the disruption to rest.
The Five Core Symptoms
RLS has a distinctive pattern that separates it from other leg discomfort. All five of these features are present in a true case:
- An urge to move your legs, usually accompanied by uncomfortable sensations. The urge itself can feel as distressing as the sensations.
- Symptoms start or worsen during rest, particularly when you’re lying down or sitting still for a stretch.
- Movement brings relief, at least partially, for as long as you keep moving. Walking, stretching, or even shifting positions helps.
- Symptoms are worse in the evening or at night than during the day, following your body’s internal clock.
- No other condition better explains the symptoms, such as arthritis, leg cramps, or poor circulation.
That last point is important. Plenty of conditions cause leg discomfort, but RLS has a specific combination of rest-triggered, movement-relieved, evening-dominant symptoms that other diagnoses don’t share.
What the Sensations Actually Feel Like
One of the frustrating things about RLS is that the sensations are genuinely hard to put into words. When researchers asked patients to describe what they feel, the most common responses were “restless” (88%), “uncomfortable” (78%), and a “need to stretch” (76%). About half described “tingling” or “jumping” sensations. People also use words like crawling, pulling, burning, prickling, or jittery. Some patients have described it as feeling like ants in their bones or carbonation running through their veins.
Deep muscular pain localized to both legs has been reported in up to 86% of patients. This catches many people off guard because they expect RLS to be purely a “weird sensation” rather than something painful. In fact, when patients are asked to spontaneously describe their symptoms without prompting, “painful” and “irritating” are each reported by about 17% of people, while 24% lead with simply describing “the urge to move.”
The sensations typically occur deep in the calves, thighs, or feet. They can affect one leg or both, though in most cases both legs are involved. Some people also feel the sensations in their arms, though this is less common and usually appears in more severe cases.
Why Symptoms Get Worse at Night
The evening and nighttime worsening isn’t just because you happen to be lying down. RLS follows a circadian pattern, meaning the symptoms are tied to your body’s internal clock. Even if you sit still for the same duration during the afternoon, the sensations are typically milder than they would be at 10 p.m. Symptoms generally peak around bedtime and into the early night hours.
This timing creates a cruel overlap with sleep. RLS delays how long it takes to fall asleep, reduces total sleep time, and causes more awakenings throughout the night. Sleep studies comparing people with RLS to healthy sleepers consistently show lower sleep efficiency, less time in deep and REM sleep stages, and more frequent shifts between sleep stages. Over weeks and months, this adds up to significant daytime fatigue, difficulty concentrating, and mood changes that people sometimes don’t connect to their legs at all.
Involuntary Leg Movements During Sleep
More than 80% of people with RLS also have periodic limb movements during sleep. These are repetitive, involuntary jerking or twitching motions that happen roughly every 20 to 40 seconds, often without you being aware of them. A bed partner may notice them first. These movements can pull you out of deeper sleep stages even if they don’t fully wake you, contributing to that unrefreshed feeling in the morning.
Periodic limb movements aren’t required for an RLS diagnosis, but they’re so common that their presence can help confirm the condition when symptoms are ambiguous.
How RLS Differs From Similar Conditions
Several conditions mimic parts of the RLS pattern, which leads to frequent misdiagnosis. Peripheral neuropathy, which involves nerve damage in the extremities, can cause tingling, burning, and pain that also worsens at night. The key difference is that neuropathy symptoms don’t improve with movement and aren’t driven by a compelling urge to move. Neuropathy also tends to cause numbness or loss of sensation, which RLS does not.
Leg cramps are sudden, painful muscle contractions with a clear start and end. RLS sensations are more diffuse, less acute, and don’t involve a visible muscle spasm. Arthritis pain is tied to specific joints, worsens with activity rather than rest, and doesn’t follow the same evening pattern. Poor circulation causes heaviness, swelling, or skin changes that differ from the deep restlessness of RLS.
In people who have both RLS and neuropathy (which does happen), the neuropathy-related RLS tends to start later in life, progresses more quickly, and affects both legs equally. Primary RLS, by contrast, can be asymmetric in about 25% of cases and often develops over years.
Severity Ranges Widely
RLS exists on a spectrum. Clinicians use a 40-point rating scale to categorize severity: scores of 1 to 10 are considered mild, 11 to 20 moderate, 21 to 30 severe, and 31 to 40 very severe. What this looks like in daily life varies enormously.
Mild RLS might mean occasional discomfort a few evenings per week that delays sleep by 15 or 20 minutes. Moderate cases involve more frequent symptoms that noticeably cut into sleep quality and make sitting through a movie or long flight genuinely difficult. Severe and very severe RLS can make it nearly impossible to rest in the evening, significantly shorten total sleep time, and start intruding into daytime hours as well, disrupting work, travel, and social activities.
Low Iron as a Common Trigger
Iron plays a central role in RLS for many people. Your brain uses iron to produce dopamine, the chemical messenger involved in movement control, and when iron stores are low, RLS symptoms can emerge or worsen. The threshold that RLS specialists watch for is a ferritin level (a blood marker of iron storage) at or below 75 micrograms per liter. This is well within the “normal” range on a standard lab report, which is why iron deficiency as a contributor to RLS often goes undetected.
If your ferritin is below that threshold, iron supplementation can meaningfully improve symptoms. This is one of the first things worth investigating if you suspect RLS, because it’s a relatively simple intervention compared to other treatments.
RLS in Pregnancy
About 22% of pregnant women develop RLS, and some estimates put the number closer to one in three. Symptoms are most aggravated in the third trimester, when iron demands are highest and circulation changes are most pronounced. The good news is that pregnancy-related RLS typically resolves after delivery, though women who experience it are at higher risk of developing RLS again later in life.
RLS in Children
Children can develop RLS starting as early as age 5 or 6, but getting a correct diagnosis is often difficult. Kids may describe the feeling as “bugs” in their legs or use other creative language that doesn’t immediately signal RLS to a parent or pediatrician. The symptoms show the same pattern as in adults: worse at rest, better with movement, and more noticeable in the evening.
One common source of confusion is “growing pains,” a vague diagnosis given to many children with nighttime leg discomfort. The distinguishing feature is that growing pains come and go without a clear relationship to rest or movement. A child with RLS will feel driven to get up and walk around or stretch, and the discomfort reliably improves when they do. Children may also struggle to sit still in classrooms or during car rides, which can be mistaken for behavioral issues rather than a neurological condition.