AROUSAL FLUCTUATIONS IN NON-RAPID EYE-MOVEMENT PARASOMNIAS - THE ROLEOF CYCLIC ALTERNATING PATTERN AS A MEASURE OF SLEEP INSTABILITY

Some non-rapid eye movement (NREM) parasomnias, such as sleepwalking ( SW), sleep terror (ST) and, in some aspects, sleep enuresis (SE), are considered ''arousal disorders'' without significant polysomnographic changes in classic sleep macrostructure. The aim of our study was to e valuate sleep microstructure and oscillations of arousal level by cycl ic alternating pattern (CAP) scoring in some NREM parasomnias. Nocturn al polysomnography and videotape recording was used to study 21 patien ts with motor and behavioral phenomena during sleep: 13 in Group A (se ven SW, six ST) with delta sleep-related episodes, eight in Group B wi th other parasomnias (six sleep bruxism and two SE), and six healthy c ontrols. Classic sleep macrostructural parameters were no different in the parasomniacs and controls. Compared with the controls, our patien ts' sleep microstructure, scored by CAP analysis, showed increases in CAP rate (a measure of NREM instability with high level of arousal osc illation), in number of the CAP cycles, and in arousals with EEG synch ronization, the increases being more significant in Group A than in Gr oup B. An increase in sleep instability and in arousal oscillation see ms to be a typical microstructural feature of delta sleep-related para somnias and probably plays a role in triggering abnormal motor episode s during sleep in these patients.