P054 A multi-Centre retrospective analysis of neural aperiodic activity as a measure of vigilance

Abstract Background The Maintenance of Wakefulness Test (MWT) is an integral component of the sleep physician’s arsenal when determining vigilance in sleepy patients. Despite this, the MWT has been controversial owing to its time–cost and lack of universally agreed reference ranges. The neural aperiodic exponent (NAE) can be generated from electroencephalogram (EEG) data collected during MWT and has been shown to be modulated by the neuronal behaviours which are altered in excessive sleepiness. Seow et al presented a pilot study in 2024 investigating NAE in patients who had undergone MWT as a novel test of vigilance. Here, we have expanded this work, presenting data from multiple public hospitals in South Australia to further understand the relationship between NAE and clinical sleepiness, and explore other EEG-derived biomarkers of sleepiness. Methods 97 patients who underwent MWT between 2009 and 2025 across Queen Elizabeth and Royal Adelaide hospitals were included. MWT were performed per guidelines published by the AASM. Patient and MWT data were collected retrospectively by review of electronic medical records. The aperiodic exponents were derived from two-minutes of eye-open EEG data from each MWT trial, via the IRASA method in MNE-Python. Progress to Date Patient demographic data has been collected for 97 patients. NAE from 50 patients have been analysed with results showing the aperiodic slope was predictive of sleep latency (p=.002). Data analysis of the remaining 47 patients is ongoing. Intended outcome and impact To further validate NAE as a viable, objective alternative to MWT to determine a patient’s vigilance.