Pediatric Pulmonology 48:1127–1134 (2013) Nocturnal Dipping Is Preserved in Children With Sleep Disordered Breathing Regardless of Its Severity Rosemary S.C. Horne, PhD, 1 * Joel S.C. Yang, PhD, 1 Lisa M. Walter, PhD, 1 Heidi L. Richardson, PhD, 1 Denise M. O’Driscoll, PhD, 1 Alison M. Foster, BSc (Hons), 1 Shi Wong, BMS (Hons), 1 Michelle L. Ng, MRepSc, 1 Farhat Bashir, MRepSc, 1 Ruth Patterson, BSc (Hons), 1 Damien Jolley, MSc, 2 Adrian M. Walker, PhD, 1 Vicki Anderson, PhD, 3 Margot J. Davey, MBBS, FRACP, 1,4 and Gillian M. Nixon, MBChB, MD, FRACP 1,4 Summary. Objective: Sleep disordered breathing (SDB) in adults has been associated with a loss of nocturnal dipping in blood pressure (BP) and heart rate, however, there have been limited studies in children. We measured BP non-invasively and continuously overnight in 105 children aged 7–12 with a range of severities of SDB and 36 non-snoring controls to examine nocturnal dipping profiles. Study Design: Children with SDB were divided into three severity groups according to their obstructive apnea hypopnea index. Nocturnal dipping profiles across sleep stages were described both as a proportion of children exhibiting a 10% fall in systolic arterial pressure (SAP) and heart rate (HR) from wake to sleep and according to SAP sleep/ SAP wake ratio as extreme dippers (ratio  0.8), dippers (ratio < 0.8 and 0.9), non-dippers (ratio < 0.9 and 1.0), and reverse dippers (ratio > 1.0). Results: The mean fall in BP be- tween wake and NREM 1/2, SWS, and REM sleep was not different between the groups and there were no differences between the dipping profiles of children in each group. Conclusions: SDB did not alter nocturnal dipping patterns of BP and HR compared to controls, a finding which may suggest that these young children have not been exposed to the effects of SDB long enough or that SDB severity was not great enough to affect nocturnal dipping profiles. However, further studies are required to determine if the elevated BP previously reported in this group of children will have long-term effects on the cardiovascular system. Pediatr Pulmonol. 2013; 48:1127–1134. ß 2013 Wiley Periodicals, Inc. Key words: blood pressure; pediatrics; sleep. Funding source: National Health and Medical Research Council of Australia, Number: 384142, Victorian Government’s Operational Infrastructure Support Programme. INTRODUCTION Blood pressure (BP) variations are closely tied to the sleep wake cycle with BP reaching its lowest levels dur- ing night time sleep and rising to a peak during the hours after awakening in the morning. 1 During sleep in adults BP falls by 10–20% from daytime levels, a change referred to as ‘‘nocturnal dipping,’’ 1 and evi- dence suggests that adults without this dipping pattern are at increased risk of hypertension. 2,3 There is strong evidence that in adults obstructive sleep apnea (OSA) is independently linked with hypertension, 4,5 with the likely mechanisms including abnormal neuro-endocrine BP control, reflected in increased BP variability and less nocturnal dipping. 4,6 OSA is at the severe end of the continuum of sleep disorders collectively referred to as sleep disordered breathing (SDB), the cardinal symp- tom of which is snoring. SDB is very common in chil- dren with the prevalence of habitual snoring (snoring often or always) being reported to occur in up to 35% of children. 7 The majority of children with SDB have 1 The Ritchie Centre, Monash Institute of Medical Research, Monash Uni- versity, Melbourne, Australia. 2 School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia. 3 Critical Care and Neuroscience Research, Murdoch Children’s Research Institute, Melbourne, Australia. 4 Melbourne Children’s Sleep Centre, Monash Children’s, Monash Medi- cal Centre, Melbourne, Australia. Conflict of interest: None. *Correspondence to: Rosemary S.C. Horne, PhD, The Ritchie Centre, Level 5, Monash Medical Centre, 246 Clayton Road, Clayton, Victoria 3168, Australia. E-mail: rosemary.horne@monash.edu Received 3 August 2012; Accepted 26 October 2012. DOI 10.1002/ppul.22727 Published online 29 June 2013 in Wiley Online Library (wileyonlinelibrary.com). ß 2013 Wiley Periodicals, Inc.