Yawning distribution across 24 hour in preterm and near term infants.

Introduction: In preterm infants, observed for short periods, yawns arescarcely present and usually associated with increased behaviouralarousal (1). The aim of this study is to analyse the frequency of yawnsas well as yawning distribution across 24 h.Method: Twelve low risk infants between 31 and 40 weeks of postconceptional age (PCA) were video-recorded for 24 h. Yawning wasdefined according to criteria published in a previous study (1). Threemotility patterns compatible with the presence of quiet sleep (P1), ofactive sleep (P2) and of wakefulness (P3) were identified (2,3).Results: The rate of yawning across the 24-h period was 1.10 per hour.Significant differences in the probabilities of yawning among the threemotility patterns were found (F = 9.26; P = 0.001), and the highestprevalence of yawning was in the wakefulness motility pattern. Nochanges of yawning distribution was found during the 24 h period(F = 1.27; NS); no differences were observed either between day andnight (t = –0.65; NS).Discussion: The frequency of yawns at early steps of development ishigher with respect to the adult (4). Different from the adult (4), whoyawns mainly at the awakening in the morning, and approaching sleeptime in the evening, preterm and near term infants don’t show apreferential distribution of yawns during the 24 h period. Since in theearly epochs of life there is no a main episode of sleep in the night as aconsequence yawns could not be concentrated in the evening withrespect to other times of day