Hawley E. Montgomery-Downs

Polysomnographic Characteristics in Normal Preschool and Early School-Aged Children

OBJECTIVE. The objective of this study was to describe overnight polysomnographic measures in normal children aged 3 to 7 years. We conducted a retrospective analysis of normal polysomnographic evaluations from participants in 2 large community-based studies of sleep-disordered breathing among preschoolers and early school-aged children at Kosair Children’s Hospital Sleep Medicine Research Center at the University of Louisville. Participants included 542 healthy children with ages ranging from 3.2 to 8.6 years. RESULTS. Subjects were excluded from analysis if they had documented snoring during polysomnography, an obstructive apnea-hypopnea index of ≥1.0, or a periodic leg-movement index of ≥5.0. Because the greatest differences in polysomnography occurred between ages 5 and 6 years, analyses were performed for children 3 to 5 years and for ages ≥6. Sleep cyclicity was distinct between age groups, with both showing an initial brief rapid-eye-movement period, which lengthened across the night, but only the older group showing a decrease in cycle length across the night. Average obstructive apnea indices were 0.03 per hour of total sleep time (TST) for 3- to 5-year-old children and 0.05 per hour of TST for ≥6-year-old children, whereas central apnea indices were 0.82 and 0.45 per hour of TST, respectively. Older children spent a greater percentage of sleep time supine, and the apnea-hypopnea index differed according to body position. Twenty percent of all subjects had end tidal carbon dioxide values of >45 mm Hg, and 2.2% had recorded values >50 mm Hg during ≥50% TST. High variance was present on all measures. CONCLUSIONS. Developmental changes occur in several polysomnographic measures among normal children from 3 to 7 years of age, particularly during transition from preschool to early school age. Our findings in a large number of healthy community children comprise the most extensive compilation of normative reference values for laboratory-based pediatric polysomnography to date.

Movement toward a novel activity monitoring device

PurposeAlthough polysomnography is necessary for diagnosis of most sleep disorders, it is also expensive, time-consuming, intrusive, and interferes with sleep. Field-based activity monitoring is increasingly used as an alternative measure that can be used to answer certain clinical and research questions. The purpose of this study was to evaluate the reliability and validity of a novel activity monitoring device (Fitbit) compared to both polysomnography and standard actigraphy (Actiwatch-64).MethodsTo test validity, simultaneous Fitbit and actigraph were worn during standard overnight polysomnography by 24 healthy adults at the West Virginia University sleep research laboratory. To test inter-Fitbit reliability, three participants also wore two of the Fitbit devices overnight at home.ResultsFitbit showed high intradevice reliability =96.5–99.1. Fitbit and actigraph differed significantly on recorded total sleep time and sleep efficiency between each other and polysomnography. Bland–Altman plots indicated that both Fitbit and actigraph overestimated sleep efficiency and total sleep time. Sensitivity of both Fitbit and actigraphy for accurately identifying sleep was high within all sleep stages and during arousals; specificity of both Fitbit and actigraph for accurately identifying wake was poor. Specificity of actigraph was higher except for wake before sleep onset; sensitivity of Fitbit was higher in all sleep stages and during arousals.ConclusionsThe web-based Fitbit, available at a markedly reduced price and with several convenience factors compared to standard actigraphy, may be an acceptable activity measurement instrument for use with normative populations. However, Fitbit has the same specificity limitations as actigraphy; both devices consistently misidentify wake as sleep and thus overestimate both sleep time and quality. Use of the Fitbit will also require specific validation before it can be used to assess disordered populations and or different age groups.

Snore-Associated Sleep Fragmentation in Infancy: Mental Development Effects and Contribution of Secondhand Cigarette Smoke Exposure

OBJECTIVE. The link between sleep-disordered breathing and neurocognitive functioning in preschool and school-aged children now has been established clearly. Within these age groups, isolated studies have examined the potential effect of snoring without gas exchange abnormalities on aspects of cognitive competence. The goal of the study was to test the potential association between snoring and decrements in developmental performance among infants. METHODS. Thirty-five healthy community infants (8.2 ± 0.4 months) were administered the Bayley Scales of Infant Development, including the Mental Development Index (MDI), after standard, overnight research polysomnography. RESULTS. The apnea-hypopnea index for all infants was 0. Respiratory arousal index was significantly correlated with MDI. Snoring-associated arousals accounted exclusively for this relationship; spontaneous arousals and those that were associated with central apnea and oxyhemoglobin desaturation episodes (≥4%) were not significantly correlated with MDI. Living in a smoking household was not significantly associated with the presence of objectively recorded snoring but was associated with an increase in arousal frequency in snoring infants. CONCLUSIONS. Infants with lower scores on a standardized mental development assessment had higher snoring-arousal indices. Because neither apnea nor hypopnea was present, these findings constitute additional evidence that snoring is not just an innocent noise during sleep in infants but may in fact represent the lower end of the disease spectrum associated with sleep-disordered breathing. Secondhand exposure to cigarette smoke may increase the deleterious effects of infant snoring.

Sleep in the family.

Family systems are dynamic, with reciprocal interactions among family members. When children have sleep problems, they often awaken a parent, affecting parent sleep and subsequent parent daytime functioning. Child sleep patterns can also be disrupted by parent cognitions related to the childs sleep, as well as when parents are experiencing external stressors (eg, work or marital problems). This article focuses on sleep in a family context, reviewing the relationship between sleep among children and their parents from infancy to adolescence. Sleep in the family when a child has a chronic illness or development disorder is also reviewed.

Sleep quality and characteristics of college students who use prescription psychostimulants nonmedically.

OBJECTIVE Although psychostimulants have been shown to affect sleep in experimental studies, the relation between nonmedical psychostimulant use and sleep has not been examined. Our goal was to describe the sleep quality and characteristics of college students who use psychostimulant medications nonmedically. METHODS We surveyed 492 college students about their sleep quality and psychostimulant use characteristics. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI); psychostimulant use and characteristics were measured via a survey developed for this study. RESULTS College students who self-reported current or a history of nonmedical psychostimulant use reported worse subjective sleep quality, sleep disturbance, and global PSQI scores than nonusers. The most commonly reported reason for nonmedical psychostimulant use was to improve work performance and concentration. CONCLUSIONS These data demonstrate worse sleep quality among nonmedical psychostimulant users. The likely consequence of increased daytime sleepiness helps to confirm the known public health concern of nonmedical prescription psychostimulant use among college students.

Infant-Feeding Methods and Childhood Sleep-Disordered Breathing

OBJECTIVE. Childhood sleep-disordered breathing has an adverse impact on cognitive development, behavior, quality of life, and use of health care resources. Early viral infections and other immune-mediated responses may contribute to development of the chronic inflammation of the upper airway and hypertrophic upper airway lymphadenoid tissues underlying childhood sleep-disordered breathing. Breastfeeding provides immunologic protection against such early exposures. Therefore, we sought to explore whether sleep-disordered breathing severity would differ for children who were breastfed as infants. METHODS. The parents or guardians of 196 habitually snoring children (mean ± SD: 6.7 ± 2.9 years old) who were undergoing overnight polysomnography at Kosair Childrens Hospital Sleep Medicine and Apnea Center completed a retrospective survey on the method(s) used to feed the child as an infant. RESULTS. Among habitually snoring children, those who were fed breast milk for at least 2 months had significantly reduced sleep-disordered breathing severity on every measure assessed, including apnea-hypopnea index, oxyhemoglobin desaturation nadir, and respiratory arousal index. Breastfeeding for longer than 5 months did not contribute additional benefits. CONCLUSIONS. Our findings support the notion that breastfeeding may provide long-term protection against the severity of childhood sleep-disordered breathing. Future research should explore mechanism(s) whereby infant-feeding methods may affect the pathophysiology of development of childhood sleep-disordered breathing.

Invalidity of one actigraphy brand for identifying sleep and wake among infants

STUDY OBJECTIVES Few commercially available brands of actigraphs (ACT) have been subjected to rigorous validation with infant participants. The purpose of this study was to examine the agreement between concurrent polysomnography (PSG) and one brand of ACT (AW-64, Mitter Co. Inc.) using appropriate statistical techniques among a sample of healthy infants. METHODS Twenty-two healthy infants (14.1+/-0.6 months) had one night of ankle ACT recording during research PSG at Kosair Childrens Hospital Sleep Research Center in Louisville, Kentucky. Macroanalyses were conducted using the Bland-Altman concordance technique to assess agreement between total sleep time (TST) and wake after sleep onset (WASO) simultaneously measured by PSG and ACT, using two ACT algorithm settings. Microanalyses were also calculated to examine sensitivity, specificity, and accuracy of ACT within each PSG-identified sleep state. Correlations were calculated between PSG-identified arousals and the discrepancies between ACT and PSG. RESULTS The Bland-Altman concordance technique revealed that ACT underestimated TST by 72.25 (SD=61.48) minutes and by > or = 60 min among 54.55% of infants. Furthermore, ACT overestimated WASO by 13.85 (SD=30.94) minutes and by > or = 30 min among 40.91% of infants. Sensitivity, specificity, and accuracy analyses revealed that ACT adequately identified sleep, but poorly identified wake. PSG and ACT discrepancies were positively associated with PSG-identified arousals (r=.45). CONCLUSIONS Improved device and/or software development is needed before the AW-64 can be considered a valid method for identifying infant sleep and wake.

Pediatric obstructive sleep apnea: A potential late consequence of respiratory syncitial virus bronchiolitis

To examine the hypothesis that children who suffered from severe respiratory syncitial virus (RSV) bronchiolitis during infancy may be at higher risk for obstructive sleep apnea (OSA) later in childhood.

Sleep disturbance and neurobehavioral performance among postpartum women.

STUDY OBJECTIVES Sleep disturbances cause neurobehavioral performance and daytime functioning impairments. Postpartum women experience high levels of sleep disturbance. Thus, the study objective was to describe and explore the relation between neurobehavioral performance and sleep among women during the early postpartum period. DESIGN Longitudinal field-based study. PARTICIPANTS There were 70 primiparous women and nine nulliparous women in a control group. INTERVENTIONS None. METHODS AND RESULTS During their first 12 postpartum weeks, 70 primiparous women wore continuous wrist actigraphy to objectively monitor their sleep. Each morning they self-administered the psychomotor vigilance test (PVT) to index their neurobehavioral performance. Nine nulliparous women in a control group underwent the same protocol for 12 continuous weeks. Postpartum PVT mean reciprocal (1/RT) reaction time did not differ from that of women in the control group at postpartum week 2, but then worsened over time. Postpartum slowest 10% 1/RT PVT reaction time was significantly worse than that of women in the control group at all weeks. Despite improvements in postpartum sleep, neurobehavioral performance continued to worsen from week 2 through the end of the study. Across the first 12 postpartum weeks, PVT measures were more frequently associated with percent sleep compared with total sleep time, highlighting the deleterious consequences of sleep disruption on maternal daytime functioning throughout the early postpartum period. CONCLUSIONS Worsened maternal neurobehavioral performance across the first 12 postpartum weeks may have been influenced by the cumulative effects of sleep disturbance. These results can inform future work to identify the particular sleep profiles that could be primary intervention targets to improve daytime functioning among postpartum women, and indicate need for further research on the effectiveness of family leave policies. The time when postpartum women return to control-level daytime functioning is unknown.

Urinary F2-isoprostane metabolite levels in children with sleep-disordered breathing

Oxidant stress-related mechanisms have been proposed as a major contributor to the increased prevalence of cardiovascular morbidity in adult patients with sleep-disordered breathing. Isoprostanes provide a reliable biomarker of oxidant injury in vivo. The purpose of the present study was to examine the hypothesis that oxidant stress, as evidenced by increased levels of F2-isoprostane metabolites (IsoP-m) in urine, is present in children with a spectrum of sleep-disordered breathing. Assays were performed on urinary samples obtained from each of 47 pediatric patients immediately upon awakening after standard overnight polysomnography. Of the subjects, 15% had mild, 9% had moderate, and 6% had severe sleep-disordered breathing. After controlling for correlations between BMI and IsoP-m and SpO2 values, IsoP-m values were unrelated to any polysomnographic measures. The absence of increased levels of urinary F2-isoprostane metabolites in children with sleep-disordered breathing suggests that oxidative stress is not a significant feature of pediatric sleep-disordered breathing.