Circadian and state-dependent core body temperature in people with spinal cord injury

Abstract

Study design: Prospective cohort study. Objectives: To analyze the circadian rhythm and state-dependent modulation of core body temperature (Tcore) in individuals with spinal cord injury (SCI) under controlled environmental conditions. Setting: Institute of the Neurological Sciences of Bologna, Italy. Methods: We assessed 48-h rectal Tcore and sleep–wake cycle by means of video-polygraphic recording in five cervical SCI (cSCI), seven thoracic SCI (tSCI), and seven healthy controls under controlled environmental conditions. Results: cSCI showed higher night-time Tcore values with reduced nocturnal decrease, higher MESOR and earlier acrophase compared with tSCI and controls (p < 0.05 in all comparisons). The mean Tcore values during wake and non-rapid eye movement (NREM) and rapid eye movement (REM) sleep stages were higher in cSCI compared with tSCI and controls (p < 0.05). Tcore variability throughout the 24 h differed significantly between cSCI, tSCI, and controls. Conclusions: cSCI had higher Tcore values without physiological night-time fall compared with controls and tSCI, and a disrupted Tcore circadian rhythm. Furthermore, SCI individuals did not display the physiological state-dependent Tcore modulation. The disconnection of the sympathetic nervous system from its central control caused by the SCI could affect thermoregulation including Tcore modulation during sleep. It is also possible that the reduced representation of deep sleep in people with SCI impairs such ability. Further studies are necessary to evaluate whether improvement of sleep could ameliorate thermoregulation and vice versa.