What do leg movements have to do with sleep?
Leg movements during sleep can lead to sleep fragmentation. This more than qualifies them as “movement disorders of sleep.” These real sleep disorders are common and usually involve the legs. However, some will experience them in their arms as well.
Many people have Restless Leg Syndrome (RLS), but may not consider it a sleep disorder. This is unfortunate: untreated RLS can make it very difficult to fall asleep at night (see video, below).
Others who have Periodic Leg Movement Disorder (PLMD) may be completely unaware of it. Often, a loved one calls attention to the rhythmic kicking, toe pointing or flexing, or other patterns of movement that disrupt their own sleep at night (video follows).
Another sleep disorder, REM Behavior Disorder (RBD) involves movement during REM sleep—when the body is normally held in a temporary paralysis. It can be violent and dangerous for both the sleeper and anyone or anything near them (see video).
All of these movements are very different from the normal spasms called hypnic myoclonia that we often experience initially while trying to fall asleep. These moments when you jerk awake aren’t related to any of the leg movement disorders described here.
Identifying the causes of leg movements during sleep is best left to professionals.
From sleep tests, they can confirm these sleep disorders. They can also help to identify whether they occur due to hidden sleep apnea, a dietary deficiency, parasomnias in general, or other underlying neurological health problems.
Restless Leg Syndrome
The jumpy, twitchy, tingling legs that you can’t seem to calm down during the day are not something to ignore.
Restless Leg Syndrome (RLS) (or Restless Legs Syndrome) is a neurologic disorder that significantly affects about three percent of adults. Those with RLS find the condition disruptive to their sleep, work, relationships, and quality of life.
This disorder typically occurs during the day, but also follows sufferers into the night, making it difficult to fall asleep.
Most experience RLS at bedtime in the form of unpleasant sensations in the legs, which feel, true to their name, restless. They might throb, or feel “creepy crawly,” or have an urgent need to move. Most people with RLS find relief in a warm bath, massage, or stretching at bedtime when these sensations occur.
There is no cure for this condition. Lifestyle corrections and some medical treatments can alleviate its symptoms.
Periodic Leg Movement Disorder (PLMD)
Approximately 80 percent of RLS sufferers also have PLMD; however, others may only have PLMD, and not RLS.
Also referred to as period limb movement disorder, PLMD is a related but separate, nighttime-only condition. It occurs when people move their extremities rhythmically as they sleep. As its name suggests, these movements happen periodically and rhythmically throughout the night in clusters.
These movements could be pointing and flexing of the feet, or a sideways or vertical repetitive movement of the foot or even the leg. Some movements are slight and may only be detected during a sleep test, while others are extreme enough to disturb a bed partner.
It’s not clear what causes PLMD, though recent research shows that narcolepsy, Parkinson’s disease, antidepressant usage, alcohol or cigarette use or abuse, or post-traumatic stress disorder may be associated with it.
Treatments for PLMD include pharmaceuticals and lifestyle changes. Drugs for Parkinson’s disease are a first line of defense, but narcotics, anticonvulsants and other prescription sleep medications can also be useful. Meanwhile, antidepressants may need to be reviewed by a physician to rule them out as a cause.
Lifestyle changes including avoidance of late meals, caffeine, nicotine, and alcohol to alleviate their condition.
REM Behavior Disorder (RBD)
However, RBD specifically involves the movement of the limbs while a person is experiencing rapid-eye movement (REM) sleep. People with RBD are described as “acting out their dreams.”
Body movement during normal REM sleep in a healthy person shouldn’t happen. A small “gate” at the brainstem usually stops the flow of signals between the brain and the body’s muscles during REM sleep (with the exception of the diaphragm and the heart, which keep the respiratory and cardiovascular systems functioning).
People with RBD lack this regulation of the neuromuscular system. This explains their unusual movements during REM sleep.
Stand-up comedian Mike Birbiglia famously characterized RBD in his biopic, Sleepwalk With Me. In the film, he recounts his unusual experiences with the sleep disorder until finally getting treatment. (Famous sleep researcher William Dement makes a cameo appearance in the movie.)
RBD may indicate the potential for the development of Parkinsonism or Lewy body dementia. For this reason, it requires accurate, clinical diagnosis. Treatment is pharmaceutical.