The effects of hyperbilirubinemia on sleep-spindle characteristics in infants

Abstract

Objective: The purpose of this study is to investigate the effect of hyperbilirubinemia on sleep-spindle characteristics. Rhythmic activities, such as sleep spindles, may be abolished by hyperbilirubinemia. Study Design: Electroencephalogram records were taken from 15 infants with hyperbilirubinemia and 18 healthy infants at the 12th week after birth. Sleep spindles of the 2 groups were compared according to location, density, duration,amplitude, frequency, asynchrony, and asymmetry. Results: In the study and control groups, the density of the spindles was found to be 76.9 ± 23.7 and 105.2 ± 33.9, respectively, in a 1-hour non-rapid eye movement sleep period. The mean durations of the sleep spindles in the study and control groups were found to be 4105 ± 802 milliseconds and 5162 ± 1075 milliseconds, respectively. There was not any difference between the groups according to the amplitude and asymmetry. However, there was a significant difference between the 2 groups in the frequency of spindles. The mean frequency was found to be 12.5 ± 0.6 Hz in the study group and 13.2 ± 0.9 in the control group. The percentage of asynchronous spindles was higher in the study group than in the control group. There was a significant negative correlation between the bilirubin levels during the newborn period and density, duration, and frequency of spindles. However, there was a significantly positive correlation between the bilirubin levels and percentage of asynchronous spindles. There was a significant negative correlation between the duration of hyperbilirubinemia and spindleamplitude. Conclusion: We suggest that studies on the critical maturation periods of sleep-spindle patterns might provide a sensitive tool for early diagnosis of neurophysiologic brain alterations during the first trimester of life in a population of at-risk children, such as jaundiced infants.