That uncomfortable, hard-to-describe urge to move your legs when you lie down at night is most likely restless legs syndrome (RLS), a sensorimotor condition that affects an estimated 5 to 10 percent of adults. It’s not random. Your body’s internal clock, iron levels, and brain chemistry converge to make symptoms peak precisely when you’re trying to fall asleep, typically between 11 p.m. and 4 a.m.
The sensation varies from person to person. Some describe it as crawling, tingling, or pulling deep inside the legs. Others say it feels like an itch they can’t scratch or a restless energy that won’t settle. The defining feature is that moving, whether stretching, walking, or even just shifting position, brings temporary relief. Sitting still makes it worse.
Why Symptoms Hit Hardest at Night
RLS has a clear circadian pattern, and the timing isn’t coincidental. The brain chemical dopamine, which helps regulate smooth, purposeful movement, follows a daily cycle. Levels peak around 8 a.m. and gradually drop to about 60 percent of that peak by evening, reaching their lowest point around 3 a.m. In people with RLS, the brain’s response to this natural dip is exaggerated.
Here’s what researchers believe happens: low iron stores in the brain lead to an overproduction of dopamine during the day, which causes the brain’s dopamine receptors to dial down their sensitivity as a protective measure. During daytime hours, when dopamine is abundant, this compensation works fine. But in the evening, when dopamine levels naturally fall, those desensitized receptors can’t pick up enough signal. The result is a functional dopamine deficit at precisely the time you’re lying still and trying to sleep. Symptoms tend to be mildest in the late morning and early afternoon, when dopamine is highest.
Interestingly, this cycle also tracks with core body temperature. Symptoms peak when body temperature hits its nightly low point. Sleep deprivation makes everything worse, but the circadian pattern holds regardless of how tired you are.
What It Does to Your Sleep
RLS doesn’t just delay sleep. A large meta-analysis of sleep studies found that people with RLS have significantly reduced sleep efficiency, meaning they spend more of their time in bed awake rather than asleep. They take longer to fall asleep initially, wake more often during the night, and spend more time awake after those awakenings. The time spent in deep and REM sleep, the most restorative stages, is measurably decreased. Overall, the sleep architecture is fragmented in ways that lead to daytime fatigue, irritability, and difficulty concentrating, even when you think you slept “enough” hours.
Common Causes and Triggers
RLS falls into two categories. Primary RLS has a strong genetic component, with several gene variants identified that each raise risk by roughly 50 to 65 percent. If a parent or sibling has it, your chances are considerably higher. Primary RLS often starts before age 40 and tends to worsen gradually over the years.
Secondary RLS is triggered or worsened by an underlying condition or deficiency:
- Low iron stores. This is the single most important modifiable factor. Even if your standard blood work looks normal, your ferritin (a measure of stored iron) may be too low. Guidelines recommend iron supplementation when ferritin falls below 75 micrograms per liter, which is well within the “normal” range on most lab reports. Many people with RLS have adequate hemoglobin but insufficient iron reserves in the brain.
- Pregnancy. Between 10 and 34 percent of pregnant women develop RLS, driven by dropping ferritin and folate, rising estrogen and progesterone, and changes in blood flow. Symptoms typically resolve within weeks of delivery as hormone levels return to normal.
- Kidney disease. Chronic kidney disease, particularly in people on dialysis, is a well-established trigger, potentially linked to elevated parathyroid hormone levels and impaired iron metabolism.
- Vitamin D deficiency. Multiple studies have found an inverse relationship between vitamin D levels and RLS severity. Lower vitamin D correlates with worse symptoms.
Medications That Can Make It Worse
Several common medications are linked to worsening RLS, and this catches many people off guard. Antidepressants are the biggest culprit. SSRIs and SNRIs (the most widely prescribed antidepressants) are associated with more than double the odds of an RLS diagnosis. Older tricyclic antidepressants carry similar risk. If your restless legs started or worsened after beginning an antidepressant, that connection is worth exploring with whoever prescribed it.
Antihistamines, the type found in most over-the-counter sleep aids and allergy medications, are also strongly associated with RLS. This is particularly frustrating because people with restless legs often reach for sleep aids, not realizing the antihistamine inside is making the underlying problem worse. Anti-nausea medications that block dopamine and certain antipsychotic medications round out the list of common offenders.
What Helps: Non-Drug Approaches
Before considering medication, several lifestyle changes can meaningfully reduce symptoms. Regular aerobic exercise is one of the most consistently supported interventions, with benefits seen in both primary RLS and cases linked to kidney disease. The key is moderate intensity. Vigorous late-night workouts can backfire.
Yoga has shown particular promise, improving both RLS symptoms and the sleep disruption that comes with them, with no side effects reported in studies of postmenopausal women. Stretching and progressive muscle relaxation are also beneficial and require short intervention periods to see results.
Pneumatic compression devices, which are inflatable leg sleeves that gently squeeze and release, have shown strong results as a supplementary therapy. They improve both symptom intensity and quality of life. Weighted blankets work on a similar principle, providing steady pressure that some people find calming, though the formal evidence is thinner.
Practical habits matter too. Reducing caffeine and alcohol, especially in the evening, can lower symptom severity. A consistent sleep schedule reinforces your circadian rhythm, which in turn helps stabilize the dopamine fluctuations driving your symptoms. Warm baths, leg massage, and cool or warm compresses before bed provide temporary relief for many people.
When It Might Need Medical Treatment
If lifestyle changes aren’t enough and your sleep is consistently disrupted, the first medical step is a blood test for ferritin. Not just iron, but specifically ferritin, since it reflects your body’s iron stores rather than what’s circulating at that moment. If your level is at or below 75 micrograms per liter, iron supplementation alone can significantly improve or even resolve symptoms. This threshold is much higher than what most labs flag as “low,” so you may need to ask specifically about the number rather than accepting a result marked “normal.”
For persistent moderate to severe RLS, prescription options exist. Treatment guidelines have shifted in recent years, moving away from dopamine-boosting medications as a first choice because they can paradoxically worsen symptoms over time, a phenomenon called augmentation. Newer approaches target different pathways in the nervous system. The right choice depends on symptom severity, other medications you take, and whether an underlying cause like iron deficiency or kidney disease is contributing.
RLS is one of the more underdiagnosed conditions in medicine, partly because the symptoms sound vague when described and partly because they only appear at rest. If your legs feel restless specifically when you lie down, the sensation improves when you move, and it’s consistently worse in the evening, that pattern is distinctive enough to point clearly toward RLS rather than simple muscle fatigue or anxiety.