0133 Sleeping Well or Sleeping Poorly: Clues from Brain Neurochemistry

Abstract

Introduction Sleep problems are prevalent throughout the population, but little is known about the brain mechanisms that differentiate good and poor sleepers. We studied the association between brain neurochemistry, as measured by proton magnetic resonance spectroscopy (1H-MRS), and sleep quality as measured by actigraphy. We hypothesized that better sleep quality would be predicted by brain metabolites indicative of greater neuronal health, neural inhibition, and reduced levels of excitatory neurotransmitters. Methods 24 healthy adults (12 females25.4±5.6 years) wore an actigraph for seven consecutive days to collect Time in Bed (TIB), Total Sleep Time (TST), Sleep Efficiency (SE), Sleep Onset Latency (SOL), and Wake After Sleep Onset (WASO), and underwent 1H-MRS neuroimaging at 3T. Metabolite data from the medial prefrontal cortex (mPFC), dorsolateral prefrontal cortex (dlPFC), and medial parietal-occipital cortex (P-OCC) were entered stepwise into a series of multiple linear regression models to predict each actigraphic outcome. Results For SE, the regression analysis yielded a significant three predictor model (adjusted R2=.59), p=.0001, including mPFC choline (Cho; β=-.60), P-OCC N-Acetylaspartate (NAA ; β=.56), and P-OCC glutamate+glutamine (Glx; β=-.33). Better SE was associated with a combination of decreased Cho within the mPFC, and increased NAA and decreased Glx within the P-OCC. SOL was predicted by mPFC Cho alone (β =.60; adjusted R2 = .33), p=.002. This suggests that greater Cho within the mPFC was associated with a longer latency to fall asleep. Finally, for WASO, the regression analysis yielded a significant two predictor model, (adjusted R2 = .39), p=.002, including mPFC Cho (β = .56), P-OCC NAA (β = -.41). This suggests that a combination of greater Cho within the mPFC and decreased NAA in the P-OCC was associated with more minutes of wake after sleep onset. Conclusion Sleep quality was predicted from brain metabolites within the medial default mode network (DMN), an interconnected system of cortical regions that is normally deactivated during effortful cognitive processing. Sleep quality was predicted by a combined pattern of metabolites consistent with greater neuronal integrity, reduced cellular turnover, and lower excitatory neurotransmitters. Findings suggest potential metabolic and neuroanatomic targets for enhancing brain health to facilitate sleep quality. Support (If Any)