The Difference in Spectral Power Density in Sleep Electroencephalography According to the Estimation of Total Sleep Time

Abstract

Objective: The discrepancy between self-reported subjective sleep time and objective sleep time varies from person to person, and the mechanism that can explain this discrepancy is unclear. This study aimed to investigate the difference in the spectral power of sleep electroencephalography (EEG) according to the estimation of total sleep time (TST).Methods: Of the 4,080 participants in the Sleep Heart Health Study, 2,363 participants with complete data from polysomnography, morning sleep survey, and spectral power of sleep EEG were included in the analysis. The participants were classified as normo-estimators (estimation of TST <±60 min), under-estimators (underestimation of TST ≤60 min), or over-estimators (overestimation of TST ≥60 min). A fast Fourier transformation was used to calculate the EEG power spectrum for total sleep duration within contiguous 30-s epochs of sleep. The sleep EEG spectral power was compared among the groups after adjusting for potential confounding factors, such as age, sex, proportion of participants with insomnia, apnea-hypopnea index, and TST.Results: Of the 2,363 participants, 1,507 (63.8%), 412 (17.4%), and 444 (18.8%) were assigned to the normo-, under-, and over-estimator groups, respectively. The power spectra during total sleep differed significantly among the groups in the delta (p=0.008) and theta bands (p=0.017) after controlling for potential confounders.Conclusion: Higher delta and theta powers were found in the under-estimators than in the over-estimators. This study suggests that differences exist in the microstructures of polysomnography-derived sleep EEG between these two groups. This study suggests that differences exist in the microstructures of polysomnography-derived sleep EEG based on differences in sleep time estimation.