Neuroimaging findings in sleep disorders: A review article

Sleep disorders including insomnia, obstructive sleep apnea (OSA), narcolepsy and REM sleep behavior disorder (RBD), significantly impair cognition, emotional wellbeing and physical health. This review synthesizes Neuroimaging evidence across major sleep disorders. It also documents knowledge gaps in the literature and provides clear next steps towards better diagnostic and therapeutic steps for sleep disorders.

PRISMA 2020 guidelines were followed for the systematic review of Neuroimaging studies on sleep disorders, with a comprehensive search of PubMed, Scopus and Google Scholar between 1997 and 2024.

A total of 93 Neuroimaging studies published between 1997 and 2024 were systematically reviewed. Insomnia is characterized by reduced gray matter volume in the prefrontal cortex and hippocampus, increased beta activity in EEG, and decreased frontal lobe metabolism, supporting the hyperarousal model. OSA is associated with cortical thinning, hippocampal atrophy, and disrupted Default Mode Network (DMN) connectivity, correlating with cognitive deficits. Narcolepsy exhibits hypothalamic atrophy, reduced orexin signaling, and abnormal thalamocortical connectivity, explaining excessive daytime sleepiness and cataplexy. Parasomnias, particularly REM sleep behavior disorder (RBD), show neurodegenerative changes in the brainstem and basal ganglia, serving as early markers for synucleinopathies like Parkinson's disease.

Multimodal Neuroimaging and electrophysiological findings provide critical insights into the pathophysiology of sleep disorders, highlighting distinct neural patterns that enhance diagnostic precision and guide targeted interventions. Multimodal imaging approaches are essential for advancing precision medicine in sleep disorder management.