Background. In major depressive disorder (MDD), patients often express subjective sleep complaints while polysomnographic studies report only subtle alterations in neural oscillations. We hypothesize that the study of aperiodic electroencephalographic (EEG) dynamics, a marker of excitation-to-inhibition balance, may bring new insights into our understanding of sleep abnormalities in MDD. Specifically, we investigate aperiodic neural activity during sleep and its relationships with the time of sleep, depression severity, and responsivity to antidepressant treatment. Methods. Polysomnography was recorded in 38 MDD patients (in unmedicated and 7d medicated states) and 38 age-matched healthy controls (N1=76). Aperiodic EEG activity was evaluated using the Irregularly Resampled Auto-Spectral Analysis with slopes' means and intra-individual variability as outcome measures. Depression severity was assessed with the Hamilton Depression Rating Scale. We replicated the analysis using two independently collected datasets of medicated patients and controls (N2=60, N3=80). Results. Unmedicated patients showed flatter aperiodic slopes compared to controls during N2 (p-value=0.002) and steeper slopes compared to their later medicated state (p-values<0.02) during all sleep stages. Within unmedicated patients, slopes were flatter during late compared to early N2 sleep (p-value=0.006). Late N2 slopes further correlated with depression severity after 7d of antidepressant treatment (r=-0.34, p-value=0.04). Variability of slopes was increased in both unmedicated (p-values<0.03) and medicated states (p-values <0.006) of patients' N2, N3, and REM sleep compared to controls. Conclusion. Flatter slopes of aperiodic EEG power with increased variability may reflect unstable, noisy neural activity due to increased excitation-to-inhibition balance, representing a new disease-relevant feature of sleep in MDD.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.