Periodic Limb Movement Disorder

Periodic limb movement disorder or PLMD is the repetitive cramping or jerking of the limbs while sleeping. The movements are repetitive and occur about every 20 to 40 seconds and usually take place in the legs, but upper extremity movements can also occur. These movements often disrupt sleep and cause daytime sleepiness. PLMD may occur with other sleep disorders and is often linked with restless leg syndrome or RLS.  However, PLMD is not the same as RLS.