Beyond oscillatory EEG activity: spectral exponent alterations and sleep misperception in insomnia disorder

Reliable electrophysiological markers of Insomnia Disorder (ID) are increasingly sought to clarify the mechanisms of Sleep State Misperception (SSM). While most studies have focused on conventional electroencephalographic (EEG) bands, the Spectral Exponent (SE), which captures the aperiodic decay in the EEG power spectrum, may serve as a global marker of sleep-related cortical dynamics. We explored SE in ID and Healthy Controls (HC) both during Sleep Onset (SO) and across the entire NREM and REM sleep periods.