Auditory arousal thresholds are higher when infants sleep in the prone position☆,☆☆,★,★★
Section snippets
Patients
Two groups of infants were studied between January 1995 and May 1996. All infants were healthy, born at term, and were admitted to join a sleep research program because of sleep-related behavior. The infants' auditory responses had been tested with audiometry after birth (Reactometer, Amplaid). None of the infants had a history of sleep problems or apnea. At the time of investigation, no signs of infection or neurologic problems were present, and none of the infants were receiving medications
Preliminary Study: Contralateral Ear Stimulation
No significant difference was seen in the frequency of polygraphic arousals or in the sound intensity needed to arouse the infants, whether their ears were free or occluded by the earplug. An auditory challenge of 50 dB(A) induced a polygraphic arousal in 12 of the 20 infants with both ears free from occlusion, and in 13 infants with the contralateral ear occluded.
Main Study: Determination of Arousal Thresholds
Of the 25 infants studied, 3 were excluded from the study because they awakened and remained awake for more than 30 minutes while
Discussion
In this study, healthy infants showed higher arousal thresholds to auditory challenges when they slept in the prone position than in the supine position. This finding could explain the reported association between infants' prone body position and a decreased tendency to arouse from sleep or to respond to environmental noises.1, 2
We cannot explain why body position influences arousal thresholds. Complex mechanisms relate auditory stimulations to arousals. The reticular formation of the brain
Acknowledgements
We thank Dr. E. Mitchell for his critical review of the manuscript.
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Cited by (0)
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From the Pediatric Sleep Unit, Erasmus Hospital and University Hospital for Children, Free University of Brussels, Belgium.
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Supported by the Fondation Nationale de la Recherche Scientifique (grant No. 9.4524.87), and the Fondation Scientifique Universitaire Erasme.
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Reprint requests: A. Kahn, Pediatric Sleep Unit, University Hospital for Children Queen Fabiola, av. JJ Crocq 15, B-1020 Brussels, Belgium.
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0022-3476/98/$5.00 + 0 9/21/83013