The relation between abnormal behaviors and REM sleep microstructure in patients with REM sleep behavior disorder

To investigate the temporal relation between rapid eye movement (REM) sleep microstructure (REMs, EMG activity) and motor events in REM sleep behavior disorder (RBD).

Polysomnographic records of eight patients with RBD were analyzed and compared with those of eight sex- and age-matched controls. We examined sleep microstructure for REM sleep with and without REMs and phasic chin EMG activity and their temporal relation to motor events on video.

All types of motor events were either more frequent in RBD patients than in controls (P<=0.007) or present solely in RBD patients. In RBD, major motor events were significantly more frequent during REM sleep with REMs than during REM sleep without REMs (violent, 84.0% vs. 16.0%, P<0.001; complex/scenic behavior, 78.1% vs. 23.2%, P<0.001; major jerks, 77.5% vs. 20.3%, P<0.001), whereas minor motor activity was evenly distributed (54.1% vs. 45.9%, P=0.889). Controls showed predominantly minor motor activity with rare myoclonic body jerks. The distribution of motor events did not differ between REM sleep with and without REMs (40.9% vs. 59.1%, P=0.262).

In RBD, major motor activity is closely associated with REM sleep with REMs, whereas minor jerks occur throughout REM sleep. This finding further supports the concept of a dual nature of REM sleep with REMs and REM sleep without REMs and implies a potential gate control mechanism of REM sleep with REMs for the manifestation of elaborate or violent behaviors in RBD.