REGULAR ARTICLE Pacifier use does not alter sleep and spontaneous arousal patterns in healthy term-born infants Alexsandria Odoi 1 , Shanelle Andrew 1 , Flora Y Wong 1,2,3 , Stephanie R Yiallourou 1,3 , Rosemary S C Horne (rosemary.horne@monash.edu) 1,3 1.The Ritchie Centre, Monash Institute of Medical Research and Prince Henry’s Institute and Monash University, Melbourne, Victoria, Australia 2.Monash Newborn, Monash Health, Melbourne, Victoria, Australia 3.Department of Paediatrics, Monash University, Melbourne, Victoria, Australia Keywords arousal: sleep, prone sleeping position, sudden infant death syndrome Correspondence Professor Rosemary SC Horne, PhD, The Ritchie Centre, Level 5 Monash Medical Centre, 246 Clayton Road, Clayton, Victoria 3168, Australia Tel: +61 3 9594 5100 | Fax: +61 3 9594 6811 | Email: rosemary.horne@monash.edu Received 28 April 2014; revised 28 July 2014; accepted 25 August 2014. DOI:10.1111/apa.12790 ABSTRACT Aim: Impaired arousal from sleep has been implicated in sudden infant death syndrome (SIDS). Sleeping in the prone position is a major risk factor for SIDS. Epidemiological studies have shown that pacifier use decreases the risk of SIDS, even when infants sleep prone. We examined spontaneous arousability in infants slept prone and supine over the first 6 months of life and hypothesised that spontaneous arousals would be increased in pacifier users, particularly in the prone position. Methods: Healthy term infants (n = 30) were studied on three occasions over the first 6 months after birth. Spontaneous cortical arousals and subcortical activations were scored and converted into frequency per hour of sleep. Results: There was no effect of pacifier use on total time spent sleeping or awake or the number of spontaneous awakenings at any age. There was also no effect of pacifier use on the frequency or duration of the total number of spontaneous arousals or on cortical arousals and subcortical activations. Conclusion: Pacifier use did not alter infant spontaneous arousability at any of the three ages studied, in either the prone or supine sleeping position. Any preventative effect of pacifiers for SIDS may be through physiological mechanisms other than increased arousability. INTRODUCTION Sudden infant death syndrome (SIDS) is still one of the leading causes of infant mortality in developed countries with around 2300 infants dying from SIDS in the United States each year (1). Sleeping a baby in the prone position, on their tummy, has been identified as a major risk factor, accounting for up to 47% of SIDS deaths in the United States (2). However, despite advice to sleep, all babies in the supine position, up to 30% of parents in the United States, continue to place their infant in the prone position to sleep (3). The final pathway for SIDS is thought to involve impaired cardiovascular control to overcome a profound hypotension, together with a failure to arouse from sleep (4). Arousal from sleep is an essential survival mechanism. Arousal increases heart rate, blood pressure, respiratory rate and most importantly can initiate a behavioural response involving lifting and turning of the head to enable escape from a potentially asphyxiating situation (5). In infants, arousal responses to both induced and intrinsic stimuli have been shown to follow a hierarchical stereotyp- ical sequence. This consists of a spinal withdrawal reflex, followed by a sigh, a startle response and thrashing limb movements, before finally progressing to a full awakening (6). As in adults, a full cortical arousal is not required to resolve any cardio-respiratory instability. In infants, partial or incomplete arousals form the dominant arousal response and arousals are scored as either subcortical activations or cortical arousals (7). Epidemiological studies have consistently shown that pacifier use decreases the risk of SIDS (8), even when infants sleep prone (9). Reflecting the strength of this evidence, the American Academy of Pediatrics has recom- mended that pacifiers are offered to infants during sleep after breastfeeding has been established (10). However, this recommendation has not been adopted by all countries Key notes  Failure to arouse from sleep is thought to be involved in sudden infant death syndrome (SIDS), and it has been suggested that regular use of a pacifier may protect against SIDS.  No differences in sleep or spontaneous arousal patterns between pacifier users and nonusers were identified in healthy term-born infants who were predominantly breastfed.  This finding needs to be replicated in a high-risk group of infants. 1244 ©2014 Foundation Acta Pædiatrica. Published by John Wiley & Sons Ltd 2014 103, pp. 1244–1250 Acta Pædiatrica ISSN 0803-5253