| Sublaterodorsal nucleus (SLD) | The pontine REM sleep-generating center that sends glutamatergic projections to the ventromedial medulla. |
| Ventromedial medulla (VMM) | Relays inhibitory signals (glycine and GABA) to spinal motor [neurons, producing the atonia characteristic of REM sleep. |
| Pedunculopontine nucleus (PPN) | Cholinergic neurons that modulate REM sleep transitions. |
| Cardiac sympathetic denervation | Reduced cardiac 123I-MIBG uptake, reflecting loss of postganglionic sympathetic neurons. |
| Olfactory dysfunction | Reduced sense of smell, reflecting olfactory bulb pathology. |
| Constipation | Reported in 40–50%; may precede RBD diagnosis. |
| Orthostatic hypotension | Impaired baroreflex function. |
| Mild | Talking, laughing, shouting, or singing during sleep; limb jerks and twitches. |
| Moderate | Reaching, grabbing, gesturing, or arm/leg movements corresponding to dream content. |
| Severe | Punching, kicking, leaping from bed, or complex violent motor behaviors. Can result in significant injury to the patient or bed partner. |
| Hyposmia | Present in 40–60% of iRBD patients; reflects early olfactory pathology. |
| Depression and anxiety | Present in 20–40%, reflecting serotonergic and noradrenergic brainstem pathology. |
| Databases | OMIMOrphanetClinicalTrialsPubMed |