0408 GRAY MATTER VOLUME REDUCTIONS IN THE THALAMUS AND NUCLEUS ACCUMBENS FOLLOWING ACUTE SLEEP CONTINUITY DISRUPTION

Abstract

Introduction: Insufficient sleep has been negatively associated with reductions in psychological and cognitive functioning and can lead to excessive daytime sleepiness. However, the effect of acute sleep loss on regional gray matter volume (GMV) changes is poorly understood. Limited evidence suggests that thalamic GMV is susceptible to alterations in normal sleep patterns. In addition, prior work in our lab has revealed that sleep continuity disruption (SCD) reduces positive affect and increases impulsivity, suggesting the mesolimbic dopaminergic reward system may be altered by sleep loss. We hypothesized that a night of SCD would produce regional GMV reductions in the thalamus and nucleus accumbens (NAc), which would be correlated with higher ratings of daytime sleepiness. Methods: Twenty healthy, good sleepers underwent a randomized, within‐subject crossover study in which the effects of SCD via forced awakenings (FA) were compared to uninterrupted sleep (US). Following a single night of FA or US, subjects rated their sleepiness (Stanford Sleepiness Scale (SSS)) and completed a magnetic resonance imaging session. T1‐weighted scans were preprocessed and mean values for region of interest (ROI) were calculated using CAT12 and SPM. Results: Whole brain analysis revealed total GMV increased following FA, however, this was not associated to any specific region. There were significant reductions in GMV in the left thalamus (p<0.005, cluster corrected) and left NAc (p=0.032, FWE small volume corrected) following FA. Additionally, increased daytime sleepiness was negatively correlated with GMV reductions in the thalamus and NAc (p<0.05). Conclusion: A single night of SCD produced an increase in total GMV, and regional GMV reductions in the thalamus and the NAc. While the thalamus has previously been implicated, to our knowledge, this is the first occurrence of reduced NAc GMV, as well as its correlation to excessive daytime sleepiness. Despite these findings, the mechanisms associated with reduced GMV selectively affecting these regions requires additional research.