Specialist Advice — 8 minutes
Periodic limb movements in sleep (PLMS)
As one of the abnormal movements that disrupt the process of falling asleep or sleeping, periodic limb movements in sleep (PLMS) involve repetitive contractions of the legs – and sometimes the arms – about every 20 to 40 seconds during the night. Most often, extension of the big toe and flexing of the foot, sometimes accompanied by flexing of the knee and hip, cause micro-arousals that result in fragmented sleep and may lead to daytime sleepiness. People who suffer from this condition are not aware they are moving, but these involuntary movements may disturb their partners, who feel as though they are being kicked.
PLMS, which affects between four and 11% of the population, can strike at any age, but is most common in people over the age of 65.[1] This disorder can exist alone, but often occurs in those with restless legs syndrome (RLS). It can also accompany other sleep disorders such as sleep apnea, insomnia and narcolepsy.
Because these movements occur during sleep, people with PLMS are not aware of them. It is often their partners who notice the symptoms. During the medical consultation, the physician will ask questions to better understand the sleep problems and determine if they may be caused by another condition or deficiency. A blood test or other tests may be done to identify the causes.
If the physician suspects PLMS, they will send the patient to a sleep centre for a polysomnography. This test is the only way to confirm the diagnosis of PLMS, since limb movements are recorded, and rule out a secondary cause such as sleep apnea.
