Sleep classification according to AASM and Rechtschaffen and Kales: effects on sleep scoring parameters of children and adolescents

Recently, the new American Academy of Sleep Medicine (AASM) rules and the old Rechtschaffen and Kales (R&K) criteria for sleep scoring have been shown to produce significantly different results in adults. The aim of this study was to describe in detail such differences in a group of normal children. Polysomnographic recordings from 45 healthy children (18 females and 27 males) aged between 3 and 16 years were scored following both systems and the results compared. Several significant differences between the two scoring systems were found: N1 (AASM) was significantly higher than S1 (R&K) while Stages N2 and R (AASM) were significantly smaller than S2 and rapid eye movement (R&K). The Kendall Tau correlation coefficient revealed a relatively low concordance between the two systems for the scoring of number of stage shifts per hour, minutes and percentage of Stage N1/S1, and of a percentage of Stage S2/N2. The significant differences between R&K and AASM scoring systems suggest taking some caution in adopting the new scoring criteria in children; these might be shown to be potentially useful if careful selection of the appropriate indicators derived from this new method is carried out, such as the percentage of N1 and the number of stage shifts, which are measures very sensitive to the occurrence of arousals in the new AASM system.