Moderate acoustic changes can disrupt the sleep of very preterm infants in their incubators

Abstract

Aim: To evaluate the impact of moderate noise on the sleep of very early preterm infants (VPI).

Methods: Observational study of 26 VPI of 26-31 weeks' gestation, with prospective measurements of sound pressure level and concomitant video records. Sound peaks were identified and classified according to their signal-to-noise ratio (SNR) above background noise. Prechtl's arousal states during sound peaks were assessed by two observers blinded to the purpose of the study. Changes in sleep/arousal states following sound peaks were compared with spontaneous changes during randomly selected periods without sound peaks.

Results: We identified 598 isolated sound peaks (5 ≤ SNR < 10 decibel slow response A (dBA), n = 518; 10 ≤ SNR < 15 dBA, n = 80) during sleep. Awakenings were observed during 33.8% (95% CI, 24-43.7%) of exposures to sound peaks of 5-10 dBA SNR and 39.7% (95% CI, 26-53.3%) of exposures to sound peaks of SNR 10-15 dBA, but only 11.7% (95% CI, 6.2-17.1%) of control periods. The proportions of awakenings following sound peaks were higher than the proportions of arousals during control periods (p < 0.005).

Conclusions: Moderate acoustic changes can disrupt the sleep of VPI, and efficient sound abatement measures are needed.

Keywords: Arousal; Noise; Preterm newborns; Signal-to-noise ratio; Sleep.