REM Phasic Activity: Across Night Behavior and Transitions to Wake

Rapid eye movements (REMs) during sleep were initially associated with dreaming, suggesting a relationship between REMs and dream content, however this hypothesis was questioned by their differences with the REMs during wakefulness and the evidence that REMs are also present in blind individuals with no visual dreaming. Successive studies have focused on the phenomenology and physiological significance of REMs during sleep. REMs are categorized as expressions of the phasic REM component, which is characterized by bursts of eye movements, whereas the tonic REM component is characterized by quiescent periods without eye movements. The study is a retrospective analysis of 105 sleep records from 15 subjects. We analyzed the two components, tonic and phasic REM, across the sleep period, the REM activity characteristics of the first 5 minutes and of last 5 minutes of REM periods across the sleep period were also assessed. Phasic activity was more represented than tonic activity across the whole night period. Higher REM activity in the first 5 minutes of the REM period was found in the second and third cycle, whereas higher REM activity in the last five minutes of the REM period was found in the fifth cycle, also showing a progressive increasing trend throughout the night period. A significant correlation was found between the activity of the first 5 minutes of the REM period and the total duration of the REM period. According to our results, the analysis of REM activity and the focus on segments of a REM period could provide more information on REM phasic activity than those obtained with the traditional REM density.