Published: 25 August 2017
This research was supported by the National Health and Medical Research Council (NHMRC, Australia) Centre for Integrated Research Understanding of Sleep (CIRUS), 571421 (to CBM, DJB, ALD, BJY, CAE, and RRG); NeuroSleep, 1060992 (to CBM, DJB, ALD, BJY, CAE, and RRG); the Cooperative Research Centre for Alertness, Safety and Productivity, Australian Commonwealth Government (to CBM, DJB, CJG, ALD, BJY, and RRG); and the Australian National Imaging Facility (to MAG).
To evaluate brain metabolites in objective insomnia subtypes defined from polysomnography (PSG): insomnia with short sleep duration (I-SSD) and insomnia with normal sleep duration (I-NSD), relative to good sleeping controls (GSCs).
PSG empirically grouped insomnia patients into I-SSD (n = 12: mean [SD] total sleep time [TST] = 294.7 minutes [30.5]) or I-NSD (n = 19: TST = 394.4 minutes [34.9]). 1H magnetic resonance spectroscopy (MRS) acquired in the left occipital cortex (LOCC), left prefrontal cortex, and anterior cingulate cortex was used to determine levels of creatine, aspartate, glutamate, and glutamine (referenced to water). Glutathione, glycerophosphocholine, lactate, myoinositol, and N-acetylaspartate measurements were also obtained. Sixteen GSCs were included for comparison. Multivariate analysis of variance was used to evaluate differences in creatine, aspartate, glutamate, and glutamine.
Aspartate and glutamine concentrations were reduced in the LOCC in I-SSD compared with I-NSD (both p < .05, d = .80–.99). Creatine displayed a nonsignificant mean reduction in I-SSD compared with I-NSD (p = .05, d = .58). Glutamine was reduced in I-SSD compared with controls (p < .05, d = .93). There were no differences in metabolites between all (I-SSD and I-NSD) insomnia patients and controls. In patients with insomnia, LOCC glutamine concentrations were found to be positively correlated with TST (r = .43, p < .05) and negatively correlated with wake-time after sleep onset (r = −.40, p < .05).
Results indicate that I-SSD is associated with reduced brain metabolites in the LOCC compared with I-NSD and control concentrations of aspartate, glutamine, and creatine.
Christopher B Miller, PhD Caroline D Rae, PhD Michael A Green, PhD Brendon J Yee, MBCHB, PhD Christopher J Gordon, PhD Angela L D’Rozario, PhD Simon D Kyle, PhD Colin A Espie, PhD, DSc Ronald R Grunstein, MD, PhD Delwyn J Bartlett, PhD
To read the full article: https://academic.oup.com/sleep/article/40/11/zsx148/4093919