Are NREM sleep characteristics associated to subjective sleep complaints after mild traumatic brain injury?

Abstract

Sleep complaints are common after mild traumatic brain injury (mTBI). While recent find-ings suggest that sleep macro-architecture is preserved in mTBI, features of non-rapid eye movement(NREM) sleep micro-architecture including electroencephalography (EEG) spectral power, slow waves(SW), and sleep spindles could be affected. This study aimed to compare NREM sleep in mTBI and healthycontrols, and explore whether NREM sleep characteristics correlate with sleep complaints in these groups.Methods:Thirty-four mTBI participants (mean age: 34.2±11.9 yrs; post-injury delay: 10.5±10.4 weeks)and 29 age-matched controls (mean age: 32.4±8.2 yrs) were recruited for two consecutive nights ofpolysomnographic (PSG) recording. Spectral power was computed and SW and spindles were automat-ically detected in three derivations (F3, C3, O1) for the first three sleep cycles. Subjective sleep qualitywas assessed with the Pittsburgh Sleep Quality Index (PSQI).Results:mTBI participants reported significant poorer sleep quality than controls on the PSQI and showedsignificant increases in beta power during NREM sleep at the occipital derivation only. Conversely, nogroup differences were found in SW and spindle characteristics. Interestingly, changes in NREM sleepcharacteristics were not associated with mTBI estimation of sleep quality.Conclusions:Compared to controls, mTBI were found to have enhanced NREM beta power. However, thesechanges were not found to be associated with the subjective evaluation of sleep. While increases in betabands during NREM sleep may be attributable to the occurrence of a brain injury, they could also be relatedto the presence of pain and anxiety as suggested in one prior study