Autonomic nerve activities during sleep in children with severe motor and intellectual disabilities

Abstract

  Objective: Children with severe motor and intellectual disabilities (SMID) often suffer from autonomic nervous system disturbances. The purpose of our study was to clarify the autonomic nerve activities during sleep in SMID. Methods: Fifteen children with SMID (mean age; 11.0±3.4 years old) from the school for the children with disabilities and 13 typically developed children (mean age; 9.9±3.4 years old) participated in this study. We recorded their gross motor activities by actigraph for monitoring sleep behaviors. Heart rate variability (HRV) was assessed by using a heart rate monitor during three consecutive 3 nights. Time of falling asleep and time of waking up were obtained through activity recordings. Autonomic nerve activities; low frequency (LF), high frequency (HF), LF/HF, during sleep were assessed by using power spectral analysis of HRV. We divided their sleep time into four periods by each two hours from sleep to awake, and calculated the average values of LF, HF and LF/HF in each period for comparing the change of autonomic nerve activity among the two groups. Results: There was no significant difference in sleep behaviors between the two groups. During the sleep time, HF was significantly lower and LF/HF was significantly higher in SMID than those in typically developed children. The LF/HF in SMID was significantly higher than those in typically developed children in all time period. Conclusions: The autonomic nerve status in SMID was suggestive of the predominance of sympathetic activity through the all sleep time by the decrease in parasympathetic activity. These findings may show that characteristics of autonomic nerve activity during sleep in SMID are associated with respiratory problems and immaturity of the ability to control autonomic nervous system in the central nervous system that caused by brain lesion.