AUDITORY AROUSAL THRESHOLDS ARE HIGHER WHEN INFANTS SLEEP IN THE PRONE POSITION

Objective: To evaluate the possibility that infants sleeping in the pr one position have higher arousal thresholds to auditory challenges tha n when sleeping in the supine position. Study design: Polygraphic reco rdings were performed for 1 night in 25 healthy infants with a median age of 9 weeks. The infants were exposed to white noises of increasing intensities while sleeping successively in the prone and supine posit ions, or vice versa. Arousal thresholds were defined by the auditory s timuli needed to induce polygraphic arousals. Results: Three infants w ere excluded from the study because they awoke while their position wa s being changed. For the 22 infants included in the analysis, more int ense auditory stimuli were needed to arouse the Infants in the prone p osition than those in the supine body position (p = 0.011). Arousal th resholds were higher in the prone than in the supine position in 15 in fants; unchanged in 4 infants; and lower in the prone position in 3 in fants (p = 0.007). Conclusions: infants show higher arousal thresholds to auditory challenges when sleeping in the prone position than when sleeping in the supine position. The finding could be relevant to mech anisms concerned with the reported association between sudden deaths a nd the prone sleeping position in infants.