Prior housing conditions and sleep loss may affect recovery from brain injury in rats: a pilot study

The purpose of this study is to understand the effect of combat-associated conditions such as sleep deprivation (SD) on subsequent traumatic brain injury (TBI). Prior to TBI (or sham surgery) induced by controlled cortical impact (CCI), rats were housed singly in chambers that prevented rapid eye movement sleep or allowed unrestricted sleep (no SD). Sensorimotor function was tested pre-SD and retested on postoperative days (PDs) 4, 7, and 14. Two additional control groups were housed socially prior to either CCI or sham surgery. CCI resulted in immediate performance deficits on sensorimotor tasks. The PD on which performance returned to baseline depended on preinjury conditions. Overall, preinjury SD+CCI resulted in an earlier recovery than no SD+CCI, and the no SD+CCI group (housed singly under conditions comparable with the SD group) recovered slower than all other groups. These data are the first to raise the possibility that recovery of sensorimotor function following TBI is affected by preinjury conditions. The data suggest that preinjury SD 24 h in duration may result in faster recovery and that novel or social isolation conditions may impede recovery. Thus, the combat environment may contribute to complexities associated with TBIs common in U.S. servicemembers.