There's probably at least one person in your office who taps their foot or shakes their leg incessantly while they work — maybe it's you. Indeed, some people concentrate better when they're able to fidget. And while "restless leg syndrome" sounds like it could explain this type of behaviour, it's actually something completely different.
Restless leg syndrome is a neurological condition, which means any sensations it causes happen in the brain more than in the legs themselves. And while it is defined by an "irresistible urge to move the legs," according to Andy Berkowski, MD, a clinical assistant professor of neurology and sleep medicine at the University of Michigan Department of Neurology, it's not related to a general inability to sit still. If you're sitting at your desk for long periods of time, you might get uncomfortable or anxious because you haven't stretched or moved around. But with restless leg syndrome, people don't feel generally restless, they feel specifically restless in their legs, he says.
"Sometimes the feeling they get is indescribable, and they have a hard time saying what it is," Dr. Berkowski says. "It can be a creepy, crawling feeling — rarely is it painful, usually it's just an uncomfortable, unpleasant feeling in the legs." These symptoms most often occur, or worsen, at nighttime, or when someone is resting for long periods of time in a confined space, like on an airplane or in a desk chair, he says.
The tricky thing about restless leg syndrome (especially in airplane-like settings) is that people generally feel relief when they're able to move, Dr. Berkowski says. That means they might pace around, toss and turn in bed, or constantly move their legs while sitting, according to the National Institute of Neurological Disorders.
While stress and anxiety seem like an obvious cause of that other kind of fidgeting, it's less clear what leads to people experiencing RLS. "We believe that people with restless leg syndrome aren't getting dopamine properly sent to the right areas of the brain in an efficient manner," Dr. Berkowski says. When dopamine is deficient or dysfunctional, then it can send signals in the brain to the area that controls sensation in the legs. But that's not the whole story.
There's a huge relationship between restless leg syndrome and iron levels in the brain, because that's the chemical responsible for transporting dopamine in the brain, Dr. Berkowski explains. That also explains why around 40 to 50% of pregnant people get restless leg syndrome, according to a 2015 study. "It's suspected that brain levels of iron start to drop during pregnancy, because the baby is basically taking up a lot of the nutrients, so the brain doesn't get as much iron," he says. For some pregnant people, restless leg syndrome occurs during the third trimester of pregnancy, and then goes away once the baby is born. But for others it starts during pregnancy and never goes away, he says.
In mild cases of restless leg syndrome, simple lifestyle changes can be enough to find relief. Moderate activity during the day can help relieve restless leg syndrome symptoms at night, but "paradoxically, extreme exertion might make it worse," Dr. Berkowski says. Taking warm baths or getting massages can help relieve symptoms, too.
And then there are some factors that can make restless leg worse, like alcohol, caffeine, and nicotine. Some prescription medications (like antidepressants) or OTC ones (like antihistamines) can bring out restless leg syndrome or make it worse, he says. "We think that's due to the changes in brain chemistry, because all those drugs have effects on dopamine in the brain indirectly."
If you are experiencing sensations in your legs that you can't explain, or that feel way different than your usual fidgeting, it's something you should ask your doctor about, Dr. Berkowski suggests. Hopefully they'll be able to help you — and your legs — rest easy.