REM sleep as a potential indicator of hyperarousal in psychophysiological and paradoxical insomnia sufferers.

STUDY OBJECTIVES: The objective was to study REM sleep macrostructure and microstructure as potential indicators of hyperarousal in insomnia by comparing good sleepers (GS) and insomnia sufferers (INS) (subdivided into psychophysiological "PSY-I" and paradoxical "PARA-I").

DESIGN: Cross-sectional comparisons of GS, PSY-I and PARA-I.

SETTING: Participants slept for 4 consecutive nights in the laboratory where PSG was recorded. Nights 2 and 3 were combined to compare REM sleep between groups.

PARTICIPANTS: Thirty-nine PSY-I, 27 PARA-I and 47 GS completed the study, comprising home questionnaires, clinical interviews and night PSG recordings. All participants were aged between 25 and 55 and met inclusion criteria for either PSY-I, PARA-I or GS.

INTERVENTIONS N/A MEASUREMENTS AND RESULTS: Results showed no between group differences on REM sleep macrostructure. As for REM sleep microstructure, PSY-I had an increased number of wake intrusions compared to PARA-I (p=.03). Subjective SE, TST and TWT were significantly correlated with the duration of REM sleep (REMD; p≤.002) and with the proportion of REM sleep for PARA-I (p≤.06).

CONCLUSIONS: REM sleep macrostructure does not seem to be an adequate indicator of hyperarousal in insomnia. However, the number of wake intrusions in REM could be used to differentiate PSY-I from PARA-I and could reflect the heightened arousal of the former group. Relationships between REM sleep duration and proportion could be linked to dream imagery activity, especially in PARA-I. Further investigations are needed to identify variables that could reflect hyperarousal and differentiate insomnia types.