Relative Cerebral Blood Flow Differences in Individuals With Insomnia Across Sleep-Wake States Compared to Good Sleeper Controls: A Sleep Neuroimaging Study Using Arterial Spin Labelling.

The pathophysiology of insomnia remains unclear. This sleep neuroimaging study used arterial spin labelling, self-report and polysomnography to compare nighttime relative cerebral perfusion in individuals with insomnia disorder (n = 11) and controls (n = 17). We hypothesised that insomnia would be associated with altered perfusion in regions involved in arousal, sleep drive and information processing. Participants completed two polysomnography and arterial spin labelling scans: a wake scan at habitual bedtime and a sleep attempt. Sleep state was determined using self-report and polysomnography. Relative perfusion maps were computed. Group by state effects were tested using analysis of variance for within and between subjects. Regression analyses tested associations between insomnia severity and baseline perfusion during the wake scan. Significance was set at p < 0.05 cluster-corrected (voxel p < 0.005, k = 14). The insomnia group showed higher relative perfusion in posterior sensory, affective and self-referential regions, and lower relative perfusion in frontal regions and basal ganglia compared to controls. During the sleep attempt, insomnia participants who were asleep showed lower relative perfusion in several frontal and basal ganglia regions compared to those who were awake, while controls showed the opposite pattern. Greater insomnia severity was associated with lower relative perfusion during the wake scan in right peri-Sylvian cortex and basal ganglia. Overall, insomnia was associated with altered nighttime relative cerebral perfusion, including increased activity in self-referential, sensory and affective regions, alongside reduced or dysregulated perfusion in frontal cortex and basal ganglia, suggesting altered arousal regulation, sleep drive and inhibitory control.