Restless leg syndrome and periodic limb movement disorder have similar symptoms and often occur together, but they are distinct conditions that require different tests and sometimes different treatments.
Restless Leg Syndrome
RLS causes uncomfortable, tingling, and painful sensations -- usually in your legs -- that make you feel like you need to move. Movement usually relieves the sensations momentarily, but they quickly return. Symptoms tend to worsen in the evening around bedtime and often lead to insomnia. RLS can be genetic, but it can also be caused by sleep apnea, kidney disease or injury, or low iron stores called ferritin. RLS can also be related to peripheral neuropathy.
Periodic Limb Movement Disorder
Sometimes called periodic limb movements of sleep, this condition causes your legs or arms to move frequently during sleep. PLMD can cause daytime drowsiness, but it often goes undetected because you aren’t aware of the movements while you’re asleep. RLS can cause PLMD.