0409 Is insomnia with objective short sleep duration related to insufficient sleep drive or physiological hyperarousal?

Abstract

Abstract Introduction IInsomnia with objective short sleep duration (OSSD) was found to be associated with higher risks of cardiometabolic disorders, and was therefore proposed to be a phenotype associated with higher physiological hyperarousal. Previous studies further reported that insomnia with OSSD had higher autonomic arousal as measured by heart rate variability (HRV) during sleep. Since sleep duration could be determined by the interplay of arousal and sleep drive and HRV during sleep could be influenced by sleep staging and quality, the present study examined the level of arousal and sleep drive prior to sleep with EEG power and HRV to further understand the phenotyping of insomnia. Methods Ninety-four insomnia patients participated in the study and went through one night of 8-hour PSG recording. They were divided, with a cut-off of PSG total sleep time of 6 hours, into two groups: an OSSD group (N=26; mean age=37.0 ±10.3; M:F=7:19; TST=286.21±87.21 min) and an objective normal sleep duration (ONSD) group (N=68, mean age=32.95 ±10.05, M:F=12: 56, TST=414.4±28.9 min). Resting-state EEG and EKG were recorded for a 6-min period, 3-min eye-opened (EO) with fixation focus and 3 mins eye-closed (EC), prior to bedtime. Results T-tests showed no significant difference in HRV measures (SDNN, RMSD, LF, HF, LF/HF) between the two groups, but shorter R-R interval for OSSD group than ONSD group. Mann-Whitney tests for EEG power showed significantly lower theta power at F3, F4, C3, C4, and O2, and higher sigma power at F3, C3, C4, O1, and O2 during EC, as well as lower theta power at C3 and higher sigma power at O2 during EO for OSSD group in comparison to ONSD group. Conclusion The results partially support that insomnia with OSSD is associated with physiological hyperarousal as indicated by faster heart rate and higher high frequency EEG power prior to sleep. However, the lower EEG theta power prior to sleep suggest that lower homeostatic sleep drive may also play a role for the insomnia with short objective sleep duration. Support (if any) Supported by Taiwan National Science and Technology Council