Parasomnias and Sleep-Related Movement Disorders
NREM vs REM parasomnias
NREM parasomnias (sleepwalking, sleep terrors, confusional arousals) arise from slow-wave sleep, often in the first third of the night, with amnesia for the event. REM sleep behavior disorder (RBD) involves dream enactment with loss of REM atonia, typically later in the night, and is associated with neurodegenerative disease. Management includes safety measures; melatonin or clonazepam may be used for RBD.
Movement disorders
Restless legs syndrome (RLS) is an urge to move the legs, worse at rest and in the evening, relieved by movement. Iron deficiency and low ferritin are common contributors; check ferritin and treat if low. Periodic limb movements occur in sleep and are scored on PSG. Sleep bruxism involves rhythmic jaw muscle activity and dental wear.
Traps
- Sleep terrors vs nightmares: terrors occur in NREM with amnesia; nightmares occur in REM with recall.
- RBD can precede Parkinson disease by years.
- RLS is clinical, not diagnosed by PSG.
- Dopamine agonists can cause augmentation in RLS; iron status matters.
Rule of thumb
Early-night events with amnesia suggest NREM parasomnia; late-night dream enactment suggests RBD.