Firefighters Have Cerebral Blood Flow Reductions in the Orbitofrontal and Insular Cortices That are Associated with Poor Sleep Quality

Shinwon Park,1,* Haejin Hong,1,2,* Rye Young Kim,1,3,* Jiyoung Ma,1 Suji Lee,1 Eunji Ha,1,2 Sujung Yoon,1,2 Jungyoon Kim1,2 1Ewha Brain Institute, Ewha Womans University, Seoul, South Korea; 2Department of Brain and Cognitive Sciences, Ewha Womans University, Seoul, South Korea; 3Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul, South Korea*These authors contributed equally to this workCorrespondence: Sujung Yoon Email sujungjyoon@ewha.ac.krJungyoon Kim Email jungyoon.kimm@ewha.ac.krPurpose: To investigate the cerebral blood flow (CBF) alterations associated with poor sleep quality and memory performance in firefighters.Participants and Methods: Thirty-seven firefighters (the FF group) and 37 non-firefighter controls (the control group) with sleep complaints were enrolled in this study. We performed brain arterial spin labeling perfusion magnetic resonance imaging (MRI) and compared the CBF between the two groups using whole-brain voxel-wise analyses. Self-reported sleep problems and actigraphy-measured sleep parameters, including the sleep efficiency, wake after sleep onset (WASO), total sleep time, and sleep latency, were assessed. Spatial working memory and learning performances were evaluated on the day of the MRI scan.Results: The FF group, relative to the control group, had lower CBF in the right hemispheric regions: Middle temporal/lateral occipital, orbitofrontal, and insular cortices. Lower CBF in the right orbitofrontal cortex was linearly associated with poor sleep quality, as indicated by lower sleep efficiency and longer WASO. The CBF of the right insular cortex was also associated with longer WASO. Despite comparable degrees of self-reported sleep problems between the two groups, the FF group had lower sleep efficiency and longer WASO in the actigraphy, and lower spatial working memory and learning performance, relative to the control group. Poor sleep efficiency was linearly associated with lower spatial working memory performance.Conclusion: These results demonstrated an association of poor sleep quality with decreased brain perfusion in the right orbitofrontal and insular cortices, as well as with reduced working memory performance.Keywords: firefighters, sleep efficiency, wake after sleep onset, cerebral blood flow, arterial spin labeling, perfusion magnetic resonance imaging