Impact of acute sleep restriction on cerebral glucose metabolism during recovery non-rapid eye movement sleep among individuals with primary insomnia and good sleeper controls.

BACKGROUND: Restricting time in bed improves insomnia symptoms, but the neural mechanisms for this effect are unknown. Total and partial acute sleep restriction may be useful paradigms for elucidating these effects. We examined the impact of acute sleep restriction on cerebral glucose metabolism during non-rapid eye movement (NREM) sleep in individuals with primary insomnia (n = 17) and good sleep (n = 19).

METHODS: Participants underwent [18 F]fluorodeoxyglucose positron emission tomography scans during baseline and recovery NREM sleep following one night of partial or total sleep restriction. We compared group differences in baseline-recovery changes, as well as main effects of group and condition (baseline vs. recovery NREM sleep), for relative regional cerebral metabolic rate for glucose (rCMRglc ), whole-brain glucose metabolism, and sleep quality.

RESULTS: Relative rCMRglc was significantly lower during recovery NREM sleep compared to baseline in the left frontoparietal cortex, medial frontal cortex, posterior cingulate cortex, and thalamus, with no significant group differences. Good sleepers, but not insomnia patients, had lower whole-brain glucose metabolism during recovery NREM sleep compared to baseline. Acute sleep restriction improved sleep quality in individual with insomnia. Subgroup analyses including only participants who underwent partial sleep restriction yielded the same pattern of findings.

CONCLUSION: Individuals with insomnia and good sleepers showed similar relative rCMRglc responses to acute sleep restriction. Brain regions showing the greatest baseline-recovery changes in both groups included regions previously shown to have smaller sleep-wake differences in patients with primary insomnia. Acute sleep restriction, and by extension sleep restriction therapy, may impact regional metabolic alterations that characterize insomnia.