1002 Endorsement Of Sleep Problems Indexes Autism Severity In Children And Adolescents: Evidence From A Large Community Sample

Introduction

Individuals with autism spectrum disorder (ASD) often experience sleep problems. A reliance on case-control studies rather than dimensional samples limit our ability to understand how sleep problems distinguish diagnosis and severity of ASD. To address this need, we present preliminary findings from a large community sample of individuals with heterogeneous autism phenotypes.

Methods

All participants (≤ 21 years) were selected from the Rhode Island Consortium for Autism Research and Treatment (RI-CART) (final n= 977; 233F; 11.27±4.13 years), a public-private-academic registry of families in Rhode Island affected by ASD-like symptoms. Participants completed the Autism Diagnostic Observation Schedule, 2nd Edition to confirm the presence of diagnosable ASD. Each caretaker also completed dimensional measures of functional impairment: Social Responsiveness Scale, 2nd edition and the Vineland Adaptive Behavior Scale (2nd/3rd editions). Caretakers were asked whether the participant suffered current/past sleep problems: yes/no. All analyses are adjusted for age, sex, race, ethnicity, caregiver education, and scale-version (e.g., 2nd/3rd ed., where applicable).

Results

Endorsement of sleep problems distinguished ASD diagnosis: a confirmed diagnosis of ASD was associated with greater prevalence of sleep problems compared to ASD diagnosis (OR: 1.58; 95% CI: 1.05,2.38; p = .028). Across the sample, endorsement of sleep problems was associated with impairments in adaptive behavior (b = -4.73; 95% CI: -7.47,-2.00045; p = .001) and social responsiveness (b = 6.72; 95% CI: 3.27,10.16; p < .001).

Conclusion

These data from a heterogenous community sample provide evidence for a link of sleep to the phenomenology of ASD. While the search for better diagnostic indicators of ASD continues, we recommend that clinicians consider a brief assessment of sleep behaviors of patients with such neurodevelopmental conditions as autism.

Support

Simons Foundation Autism Research Initiative, Hassenfeld Child Health Innovation Institute at Brown University. K01MH109854 (JMS), NIGMS Advance CTR (JMS). KNAW Ter Meulen Grant (MEKV).

0312 Performance on a Cognitive Interference Task in Children After One-Night of Sleep Restriction

Introduction

Short sleep contributes to attention failure in conditions such as ADHD. Whether sleep loss affects attentional processes as a task varies in cognitive interference is unclear. We used a multi-source interference task (MSIT) in a sleep restriction paradigm in children with a range of ADHD symptoms to examine how short sleep disrupts attention in these youth.

Methods

Thirteen children (7F, 11.7±1.28 years) with a range of ADHD symptom severity completed a repeated-measures experiment on two consecutive nights in the laboratory: baseline (BSLN; 9.5h time-in-bed) and sleep restriction (SR; 4h time-in-bed). Each morning they took part in an fMRI session including the MSIT, in which participants respond to a series of 3-digit numbers by indicating which digit is different on no-interference (e.g., 003; correct=3) or interference (e.g., 311, correct=3) trials. Performance measures were inverse reaction time (1/RT) and accuracy. A two-way within-subject ANOVA assessed performance across interference and sleep conditions respectively.

Results

1/RT showed main-effects of sleep loss (BSLN vs. SR; F(1,148)=4.01;p<0.05;η 2=0.026) and trial type (no-interference vs. interference; F(1,148)=24.7;p<0.001;η 2=0.143). Responses were slower for interference (BSLN RT: 799.3ms, SR RT: 895.8ms) than no-interference (BSLN RT: 653.2ms, SR RT: 697.4ms) trials. No interaction between interference and sleep loss was found (F(1,148)=0.11;p>0.05;η 2=0.001). Likewise, accuracy was lower (F(1,148) = 31.1, p<.001;η 2=0.174) in interference trials (73.5%) than in no-interference trials (92.2%), however with no effect of sleep loss, nor an interaction of interference and sleep loss (all p’s > .05).

Conclusion

These data provide evidence that partial sleep loss disrupts attention processes in children, yet these differences do not appear to depend on cognitive interference in our sample. Future analyses will examine whether ADHD symptoms distinguish individual differences, as well as analyze fMRI data to probe neural processes underlying attention control.

Support

K01MH09854 (to JMS); Brown University UTRA (to GDQC).

0257 Preliminary Findings: Attentional Bias for Food Cues Unrelated to Time Awake or Circadian Phase During Forced Desynchrony in Adolescents

Introduction

Sleep quantity and quality influence attentional bias, and attentional bias for food cues has been associated with body weight. Whether the endogenous circadian cycle and/or time from awakening to bedtime contribute to attentional bias for food and differences in weight remain unclear. Using a 28-h forced desynchrony (FD) design, we hypothesized that adolescents with overweight (OW) and obesity (O) would have more attentional bias for food cues later in the wake episode and at a later circadian phase compared to adolescents with a healthy weight (HW).

Methods

50 (28 male) adolescents (12-15yr) completed 7 FD cycles. Participants completed an attentional bias task that included three food word categories (savory, sweet, fruits/vegetables) and one non-food word category (school supplies). The task was completed at 6 fixed times each cycle: Task 1 was 1.3h after scheduled awaking, Task 2 was 2h after Task 1, and Tasks 3–6 followed at 3-h intervals. Weight categorization used body mass index (BMI) percentiles (CDC): HW (>5th and <85th; n=24), OW (85th and <95th; n=13), or O (≥95th; n=14). Endogenous circadian period was determined using salivary melatonin onsets (Mean: HW=23.88h; OW=24.01h; O=23.86h). Effect of circadian phase and time since scheduled awakening was assessed by mixed effects modeling using 6 circadian and 6 time-awake bins.

Results

We found no significant differences between weight groups in attentional bias for any of the food categories (p’s >.05). We also saw no significant time awake effects or circadian influence on attentional bias, nor did time awake or circadian phase moderate the associations between weight category and attentional bias (p’s >.05).

Conclusion

Weight groups did not impact food-related attentional bias across the wake episode or circadian phase. Future directions will explore whether attentional bias for food types predicts food choice and food consumption in this study.

Support

DK101046

0983 Sleep Associated With Executive Functioning Among Adolescents Across The Adhd Continuum

Introduction

Executive functioning (EF) deficits are a key feature of ADHD, and sleep disturbances may be an important contributor. Specifically, disturbed sleep is prevalent in ADHD and similar EF deficits are observed in ADHD and sleep disorders. Associations between disrupted sleep and EF in ADHD are poorly understood, particularly during adolescence. This study is among the first to examine relationships between sleep and EF using polysomnography (PSG) among adolescents across the ADHD symptom continuum.

Methods

In this ongoing study, 42 adolescents aged 13 to 17 (mean age = 14.86, 20 females) completed 3 nights of at-home PSG recording (total sleep time; TST) and self-reports of sleep quality, daytime sleepiness, and chronotype. Seventeen had ADHD and 25 were healthy controls (HC). Participants and parents also completed a measure of EF (BRIEF-2; global and behavioral, emotional, and cognitive subscales). Linear regressions controlling for age and sex evaluated associations between sleep and EF.

Results

Self-reported poorer sleep quality and greater daytime sleepiness and eveningness tendency (p’s<.05), but not TST, were associated with poorer self-reported global EF among adolescents. Shorter TST and greater eveningness were correlated with poorer parent-reported global EF (p’s<.05). Follow up analyses examine differential relationships between sleep and behavioral, emotional, and cognitive domains of EF and between ADHD and HC groups.

Conclusion

This study is among the first to examine relationships between sleep and EF across the ADHD continuum in an adolescent-specific sample using PSG. Objectively-measured TST as well as subjective measures of sleep were associated with poorer EF in adolescents across the ADHD continuum. Prevention/intervention strategies focused on sleep may support EF among adolescents, and future studies should examine this possibility. In addition, given variability in EF among individuals with ADHD, future studies should investigate whether sleep disturbances identify a phenotypic subgroup within ADHD at risk for EF deficits.

Support

This work was supported by NIMH K23 MH108704 (Dr. Lunsford-Avery)

0408 Myths About Infant, Child, and Adolescent Sleep: Addressing False Beliefs That Hinder Sleep Health During These Crucial Developmental Stages

Introduction

Sleep is vital for healthy development from infancy through adolescence. Despite its importance, false beliefs that conflict with scientific evidence (myths) may be common among caregivers and impair sleep health during these crucial stages.

Methods

Researchers compiled a list of potential myth statements using internet searches of popular press and scientific literature. We utilized a Delphi process with experts (n=12) from the fields of pediatric, sleep, and circadian research and clinical practice. Selection and refinement of myths by sleep experts proceeded in three phases, including: focus groups (Phase 1); email-based feedback to edit, add, or remove myths (Phase 2); and closed-ended questionnaires (Phase 3) where experts rated myths on two dimensions: (1) falseness and (2) public health significance using 5-point Likert scale: 1 (“not at all”) to 5 (“extremely false/important”).

Results

Thirty-two sleep myths were identified across three developmental categories: infant (14 myths), child (6 myths), and adolescent (12 myths). Mean expert ratings illuminated the most pressing myths in each developmental category: infant sleep (“Sleep training causes psychological harm, including reduced parent-child attachment:” falseness =4.7, s.d.=0.7; public health significance=4.0, s.d.=1.1); child sleep (“Heavy, loud snoring for my child means he’s sleeping deeply:” falseness=4.8, s.d.=0.6; public health significance=4.7, s.d.=0.7), and teenager sleep (“Falling asleep in class means your teenager is lazy and not motivated:” falseness=4.8, s.d.=0.5; public health significance=4.3, s.d.=0.8).

Conclusion

The current study identified commonly-held myths about infant, child, and adolescent sleep that are not supported by (or worse, counter to) scientific evidence. If unchecked, these myths may hinder sleep at a critical developmental stage. Future research may include public health education to correct myths and promote healthy sleep among infants, children, and teenagers.

Support

5T32HL007901

0250 The Day-to-Day Associations Between Sleep Characteristics, Affect, and Affect Reactivity

Introduction

Despite the high co-occurrence of sleep and mood disturbances, day-to-day associations between sleep characteristics (sleep duration, continuity, timing) and dimensions of mood (positive affect, PA, and negative affect, NA) remain unclear. Few field studies have tested whether sleep changes may affect mood by altering people’s emotional response to daily experiences outside the laboratory. The current study aimed to examine how sleep characteristics influence affective states and a measure of emotional response to daily experiences—affect reactivity.

Methods

Participants were healthy, midlife adults (30–54 yrs old, N =462, 47% male) drawn from the Adult Health and Behavior Project- Phase 2 study. Sleep was measured with actigraphy across a 4-day monitoring period; hourly self-report measures of affect, work demand, and social interactions were collected via ecological momentary assessment. Affect reactivity was quantified as hour-to-hour changes in affect following these daily experiences. We used hierarchical linear modeling to examine whether sleep characteristics on a given night predicted average daily affect and moderated affect reactivity the following day.

Results

When participants slept later than their average sleep time on a given night, they reported greater NA the following morning (before 12pm) and afternoon (12-6pm; B’s =.03, p’s<.05). When participants slept longer than their average sleep duration, they subsequently reported greater NA throughout the following day (B’s =.02, p’s<.05). Sleep efficiency was unrelated to affect report (p’s >.05). While episodes of greater work demand and social conflict predicted lower PA and higher NA (p’s<.05), participants’ sleep characteristics did not moderate these associations (p’s>.05).

Conclusion

Overall, our findings suggest proximal associations between sleep characteristics and next-day mood. While previous studies have shown effects of sleep disruptions on affect reactivity, we did not observe such associations in the context of small, day-to-day fluctuations in sleep characteristics among healthy individuals.

Support

National Institutes of Health Grant PO1 HL040962 (to S.B.M.).

Dissipation of sleep pressure is stable across adolescence

The sleep electroencephalogram (EEG) undergoes many changes during adolescence. We assessed whether sleep homeostasis is altered across adolescent development using two measures: the dissipation of slow-wave activity (SWA, 0.6-4.6Hz) across the night and the rate of build-up of SWA in the first non-rapid eye movement (NREM) sleep episode. Furthermore, we examined the association between homeostatic and circadian measures, by correlating the build-up of SWA in the first non-rapid eye movement (NREM) sleep episode with circadian phase. Finally, we compared the dissipation of SWA in individuals with (PH+) and without (PH-) a parental history of alcohol abuse/dependence. Twenty children (8 PH+) and 25 teens (10 PH+) underwent two consecutive polysomnographic recordings at ages 9/10 and 15/16 years and again 1.5-3 years later. Thirteen young adults (ages 20-23 years; no PH+) were assessed one time. The decay of Process S was modeled for each individual at each assessment using data from both recordings. Four parameters of Process S were derived for EEG derivation C3/A2: time constant of the decay, lower asymptote (LA), the level of S at sleep onset (S(SO)), and S(SO) minus LA. We found no change in these parameters between assessments for the children and teen cohorts. Between-subject analysis of the follow-up assessment for children (ages 11-13 years) and the initial assessment for teens (ages 15/16 years) showed no difference in these parameters, nor did follow-up assessment of teens (ages 17-19 years) compared to the single assessment of young adults (ages 20-23 years). Similarly, we observed no developmental changes in the rate of the build-up of SWA in the first NREM sleep episode for our within- and between-subject analyses, or a correlation between this measure and circadian phase for either cohort. With regard to parental alcohol history, we found no difference in the dissipation of sleep pressure between PH+ and PH- children and teens. These results indicate that the dissipation of sleep pressure does not change across adolescent development, is not correlated with circadian phase, and does not differ between PH+ and PH- children and teens.

Developmental changes in brain connectivity assessed using the sleep EEG

Adolescence represents a time of significant cortical restructuring. Current theories posit that during this period connections between frequently utilized neural networks are strengthened while underutilized synaptic connections are discarded. The aim of the present study was to examine the developmental evolution of connectivity between brain regions using the sleep EEG. All-night sleep EEG recordings in two longitudinal cohorts (children and teens) followed at 1.5-3 year intervals and one cross-sectional cohort (adults) were analyzed. The children and teen cohorts were 9/10 and 15/16 years at the initial assessment; ages of the adults were 20 to 23 years. Intrahemispheric, interhemispheric, and diagonal coherence was measured between all six possible pairings of two central (C3/A2 and C4/A1) and two occipital (O2/A1 and O1/A2) derivations during slow wave, stage 2, and, REM sleep. Within-subjects analyses were performed for the children and teen cohorts, and a linear regression analysis was performed across every assessment of all cohorts. Within-subject analyses revealed a maturational increase in coherence for both age cohorts, though the frequencies, sleep states, and regions differed between cohorts. Regression analysis across all age cohorts showed an overall linear increase in left and right intrahemispheric coherence for all sleep states across frequencies. Furthermore, coherence between diagonal electrode pairs also increased in a linear manner for stage 2 and REM sleep. No age-related trend was found in interhemispheric coherence. Our results indicate that sleep EEG coherence increases with age and that these increases are confined to specific brain regions. This analysis highlights the utility of the sleep EEG to measure developmental changes in brain maturation.

Adolescent changes in the homeostatic and circadian regulation of sleep

Sleep deprivation among adolescents is epidemic. We argue that this sleep deprivation is due in part to pubertal changes in the homeostatic and circadian regulation of sleep. These changes promote a delayed sleep phase that is exacerbated by evening light exposure and incompatible with aspects of modern society, notably early school start times. In this review of human and animal literature, we demonstrate that delayed sleep phase during puberty is likely a common phenomenon in mammals, not specific to human adolescents, and we provide insight into the mechanisms underlying this phenomenon.

Effects of acute sleep restriction on behavior, sustained attention, and response inhibition in children

This study examined the effects of acute sleep restriction on the day-time behavior and performance of healthy children and adolescents. 82 participants (8 to 15 years of age) completed 5 nights of baseline sleep and were randomly assigned to Optimized (10 hr.) or Restricted (4 hr.) sleep for an overnight lab visit. Behavior, performance, and sleepiness were assessed the following day. Sleep restriction was associated with shorter daytime sleep latency, increased subjective sleepiness, and increased sleepy and inattentive behaviors but was not associated with increased hyperactive-impulsive behavior or impaired performance on tests of response inhibition and sustained attention. Results are discussed in terms of current theories regarding effects of inadequate or disturbed sleep among children and adolescents.

Extended nights, sleep loss, and recovery sleep in adolescents

In summary, this study of sleep in adolescents on an atypical schedule of 18-hour nights showed marked but not unanticipated differences in sleep as function of prior sleep deprivation. Unanticipated was the evidence of "recovery" sleep in adolescents who not only were not sleep deprived, but who had been on a sleep "optimizing" schedule and had been awake for only 10 hours. Extended sleep beginning about 4 hours in advance of entrained sleep onset phase was not associated with a return of SWS, a finding coinciding with predictions from studies in adults. Finally, this study provides an indication that the homeostatic sleep/wake process becomes less robust or sleep responsive during adolescent development, a phenomenon that may influence the delay of sleep common in adolescents.

Developmental features of sleep

In sum, sleep disorders are common problems for children and adolescents, with estimates indicating that approximately 20% to 25% of the pediatric population experiences some type of sleep disturbance. Furthermore, clinicians should be aware that sleep disturbances may not only exist in isolation, but can be related to psychiatric or medical issues. Although much appears to be known about sleep disorders in the pediatric population, our knowledge of this area is still in its infancy. Additional research is still needed to investigate differences in clinical presentation of specific sleep disturbances among different age groups (i.e., children, adolescents, adults, and elderly), to develop the most appropriate treatments for given populations, and to study the effects of sleep disturbances on functioning. Given the prevalence of these problems in the child and adolescent population and its likely impact on cognitive and behavioral functioning, health professionals need to become increasingly aware of and knowledgeable about sleep and sleep disorders. We all spend about one third of our lives sleeping, or trying to sleep; thus, we should understand as much as we can about it.

Estimating sleep patterns with activity monitoring in children and adolescents: how many nights are necessary for reliable measures?

STUDY OBJECTIVES

This study provides estimates of reliability for aggregated values from 1 to 7 recording nights for five commonly used actigraphic measures of sleep patterns, reliability as a function of night type (weeknight or weekend night), and stability of measures over several months.

DESIGN AND SETTING

Data are from three studies that obtained 7 nights of actigraph data (using Mini Motionlogger actigraphs and associated validated algorithms [ASA]) on children and adolescents living at home on self-selected sleep-wake schedules.

PARTICIPANTS

Participants were 169 children aged 12-60 months, and 55 adolescents aged 11-16 years.

MEASUREMENTS AND RESULTS

Up to 28% of weekly recordings may be unacceptable for analysis in young participants because of illness, technical problems, and participant noncompliance; studies aiming to collect 5 nights of actigraph data should record for at least 1 full week. Reliability estimates for values aggregated over any 5 nights were adequate (> or = .70) for sleep start time, wake minutes, and sleep efficiency. Measures of sleep minutes and sleep period were less reliable and may require 7 or more nights for estimates of stable individual differences. Reliability for 1- or 2-night aggregates were poor for all measures. We found significant and high correlations between summer and fall session measures for all five variables when weekend nights were included.

CONCLUSIONS

Five or more nights of usable recordings are required to obtain reliable actigraph measures of sleep for children and adolescents.

Intrinsic circadian period of adolescent humans measured in conditions of forced desynchrony

Circadian timing was assessed with forced desynchrony (FD) in 10 healthy adolescents (five boys, five girls; mean age 13.7 years). Following 10 days of entrainment to a fixed light-dark (LD) schedule at home, participants were studied under dim light (<20 lux) in the laboratory. A 28-h schedule (FD) was imposed for 12 x 28-h cycles. Saliva was collected at 30- or 60-min intervals throughout; core temperature was measured in constant routines (CR) before and after FD. Intrinsic circadian period was estimated by linear regression using temperature minimum from CRs and dim-light salivary melatonin onsets and offsets from FD. Average intrinsic circadian period for core temperature (n = 7) was 24.30+/-0.20, for melatonin onset was 24.33+/-0.21, and for melatonin offset was 24.35+/-0.21. Intrinsic circadian period in every adolescent was greater than 24 h.

Adolescent sleep patterns, circadian timing, and sleepiness at a transition to early school days

STUDY OBJECTIVES

This study examined effects on adolescent sleep patterns, sleepiness, and circadian phase of a school transition requiring an earlier start.

DESIGN AND SETTING

Adolescents were evaluated in 9th and 10th grades; school start time in 9th grade was 0825 and in 10th grade was 0720. Assessments at each point included 2 weeks of actigraphy and sleep diaries at home, followed by a 22-hour laboratory evaluation, including evening saliva samples every 30 minutes in dim light for determination of dim-light salivary melatonin onset phase (DLSMO), overnight sleep monitoring, and multiple sleep latency test (MSLT).

PARTICIPANTS

Twenty-five females and 15 males, ages 14 to 16.2 were enrolled; 32 completed the study in 9th grade and 26 completed in 10th grade.

INTERVENTIONS

Participants kept their own schedules, except that laboratory nights were scheduled based upon school-night sleep patterns.

MEASUREMENTS AND RESULTS

According to actigraphy, students woke earlier on school days in 10th than in 9th grade, but they did not go to sleep earlier and they slept less. DLSMO phase was later in 10th grade (mean = 2102) than 9th grade (mean = 2024). Sleep latency on MSLT overall was shorter in 10th (mean = 8.5 minutes) than in 9th (mean = 11.4 minutes), particularly on the first test of the morning at 0830 (5.1 vs 10.9 minutes). Two REM episodes on MSLT occurred in 16% of participants in 10th grade; one REM episode occurred in 48%. When those with REM sleep on one or both morning MSLTs (n = 11) were compared to those without morning REM, significant differences included shorter sleep latency on the first test, less slow wave sleep the night before, and later DLSMO phase in those who had morning REM.

CONCLUSIONS

Early start time was associated with significant sleep deprivation and daytime sleepiness. The occurrence of REM sleep on MSLT indicates that clinicians should exercise caution in interpreting MSLT REM sleep in adolescents evaluated on their "usual" schedules. Psychosocial influences and changes in bioregulatory systems controlling sleep may limit teenagers' capacities to make adequate adjustments to an early school schedule.

Sleep schedules and daytime functioning in adolescents

Sleep and waking behaviors change significantly during the adolescent years. The objective of this study was to describe the relation between adolescents' sleep/wake habits, characteristics of students (age, sex, school), and daytime functioning (mood, school performance, and behavior). A Sleep Habits Survey was administered in homeroom classes to 3,120 high school students at 4 public high schools from 3 Rhode Island school districts. Self-reported total sleep times (school and weekend nights) decreased by 40-50 min across ages 13-19, ps < .001. The sleep loss was due to increasingly later bedtimes, whereas rise times were more consistent across ages. Students who described themselves as struggling or failing school (C's, D's/F's) reported that on school nights they obtain about 25 min less sleep and go to bed an average of 40 min later than A and B students, ps < .001. In addition, students with worse grades reported greater weekend delays of sleep schedule than did those with better grades. Furthermore, this study examined a priori defined adequate sleep habit groups versus less than adequate sleep habit groups on their daytime functioning. Students in the short school-night total sleep group (< 6 hr 45 min) and/or large weekend bedtime delay group (> 120 min) reported increased daytime sleepiness, depressive mood, and sleep/wake behavior problems, ps < .05, versus those sleeping longer than 8 hr 15 min with less than 60 min weekend delay. Altogether, most of the adolescents surveyed do not get enough sleep, and their sleep loss interferes with daytime functioning.

Parental report of sleep problems in children with attentional and learning disorders

This study examined whether parents of children diagnosed with neurodevelopmental disorders (n = 79) report greater sleep-related problems in their offspring than do parents of normal community-based children (n = 86) on a research questionnaire developed to assess sleep and breathing problems, sleepiness, and behavioral problems. Clinical subgroups included: attention deficit/hyperactivity disorder (ADHD) (n = 43), learning disabilities (LD) (n = 11), and combined ADHD/LD (n = 25). Analyses revealed that parents of children with neurodevelopmental disorders report greater problems along all three dimensions than parents of normal control children. Sleep-related difficulties were reported at the same frequency across all three clinical subgroups. No significant difference between clinical and control groups was noted, however, in the reported length of sleep on weeknights. These preliminary findings suggest that sleep-related problems need to be routinely reviewed as part of the clinical evaluation of neurodevelopmental problems, because they may contribute to and/or exacerbate the behavioral manifestation of these disorders.

An approach to studying circadian rhythms of adolescent humans

The "long nights" protocol was designed to evaluate sleep processes and circadian rhythm parameters in young humans. A total of 19 children (10 boys, ages 11.2 to 14.1 years [mean = 12.7 +/- 1.0], and 9 girls, ages 12.2 to 14.4 years [mean = 13.1 +/- 0.7]) took part in the study. Sleep/wake initially was assessed at home using actigraphy and diary for 1 week on each child's self-selected schedule followed by an 8-night fixed light-dark (LD) condition, while sleeping from 22:00 to 08:00 h and wearing an eye mask to exclude as much light as possible. Phase measurements included 4-night mean actigraphically estimated sleep onset and offset as well as 1-night dim light salivary melatonin onset (DLSMO) phase at the end of each condition. Subjects then lived in the laboratory for 6 consecutive cycles: Day 1 LD = 14:10 h, lights out 22:00 to 08:00 h; Days 2-4 LD = 6:18 h, lights out 18:00 to 12:00 h; Days 5-6 = constant routine in continuous dim light (about 20 lux); Night 6 = 14 h recovery sleep. Phase markers (sleep onset, sleep offset, DLSMO) were significantly less dispersed after the fixed LD as compared to the self-selected condition, indicating efficacy of the LD protocol. Phase markers were correlated at the self-selected assessment (sleep onset vs. sleep offset r = .72; DLSMO vs. sleep onset r = .82; DLSMO vs. sleep offset r = .76) but not on the fixed schedule, probably due to restricted range. The constant routine provided additional phase markers, melatonin offset and midphase. Offset phase of melatonin secretion was significantly correlated with age (r = .62) and Tanner stage (r = .62). In conclusion, these preliminary data indicate a relationship between adolescent development and circadian phase. Thus, the long nights protocol is a feasible way in which to assess circadian parameters in young humans as well as to examine intrinsic sleep processes.

Effects of menopause and nasal occlusion on breathing during sleep

Prevalence of sleep-disordered breathing (SDB) is reported to increase in menopausal women. We examined response to a nocturnal respiratory challenge (nasal occlusion) during overnight polysomnography in 31 women (45 to 55 yr). Thirteen were premenopausal, four perimenopausal, and 14 postmenopausal by history and hormonal assay. Nasal occlusion increased the apnea hypopnea index (AHI) (occlusion mean = 6.6 +/- 8.0 versus baseline mean = 1.6 +/- 2.6, p < 0.01) and arousal index (occlusion mean = 35.1 +/- 20.1 versus baseline mean = 20.7 +/- 11.6, p < 0.001), but did not change the oxygen saturation nadir in those with respiratory events (occlusion mean = 91.8 +/- 4.2 versus baseline mean = 92.0 +/- 11.6). Menopausal groups did not differ on AHI, arousal index, or oxygen saturation nadir in either condition. Key variables were compared between occlusion responders (n = 11) and nonresponders (n = 20). Responders and nonresponders were not distinguished by age, menopausal status, nor several cephalometric or anthropometric variables. Body mass index (31.1 +/- 8.5 versus 24.3 +/- 3.4, p < 0.003), neck circumference (34.0 +/- 2.5 versus 32.5 +/- 1.7 cm, p < 0.05), and mandibular-hyoid distance (18.5 +/- 3.8 versus 14.5 +/- 5.7 mm, p < 0.05) were greater in responders. These findings suggest hormonal factors may be less important than weight and facial morphology in midlife development of SDB in women.

Environmental noise as a cause of sleep disruption in an intermediate respiratory care unit

Our laboratory previously reported continuously monitored peak sound levels in several areas at Rhode Island Hospital. The number of sound peaks greater than 80 A-weighted decibels (dBA) was found to be high in the intensive and intermediate respiratory care unit (IRCU) areas, even at night. Environmental noise of this magnitude is potentially sleep-disruptive. Therefore, we hypothesized that nocturnal peak sound levels of > or = 80 dBA would be associated with an increase in EEG arousals from sleep in patients in the IRCU. Six patients underwent sleep monitoring while environmental peak sound levels were continuously recorded. Each 8-hour period (2200 to 0600 hours) was broken down into 30-minute segments. If there were 10 minutes or more of wakefulness in a segment, that segment was dropped from further analysis. Of the remaining 61 segments, there was a very strong correlation (r = 0.57, p = 0.0001) between the number of sound peaks of > or = 80 dBA and arousals from sleep. These 61 periods were then classified as quiet, moderately loud, and very loud based on the number of sound peaks (< or = 5, 6-15, and > 15, respectively). Analysis of variance revealed a significant difference between the number of arousals (p = 0.001) in quiet periods and that in very loud periods. We conclude that environmental noise may be an important cause of sleep disruption in the IRCU.

The effects of regularizing sleep-wake schedules on daytime sleepiness

The present study evaluated the differential effects of two manipulations of sleep-wake schedules on daily subjective ratings of daytime sleepiness of college undergraduate students. Two experimental conditions were compared: a sleep only group and a regularity group. Subjects in both conditions were given a lower limit for total sleep time (7.5 hours). Subjects in the regularity group received an additional instruction to keep a regular sleep schedule. The study was longitudinal and prospective. Following a baseline period (12 days), the experimental conditions were introduced. The experimental phase lasted 4 weeks and overall compliance was good. A follow-up phase (1 week) began 5 weeks past termination of the experimental phase. The findings indicated that when nocturnal sleep is not deprived, regularization of sleep-wake schedules is associated with reduced reported sleepiness. Subjects in the regular schedule condition reported greater and longer lasting improvements in alertness compared with subjects in the sleep only condition and reported improved sleep efficiency.

Sleep, breathing, and cephalometrics in older children and young adults. Part II -- Response to nasal occlusion

STUDY OBJECTIVES

We postulated that nasal occlusion would provide a challenge enabling us to assess factors predisposing development of sleep apnea in older children/adolescents and young adults. Factors of interest included sex, age, body mass index (BMI), tonsillar hypertrophy, and cephalometric measurements.

DESIGN

Sleep and breathing variables were examined and compared for four groups of subjects between one baseline night and one night of nasal occlusion in a sleep research laboratory.

SUBJECTS

Healthy, normal boys (n=23, mean age=13.3+/-2.1 years), girls (n=22, mean age=13.8+/-1.8 years), men (n=23, mean age=22.2+/-1.5 years), and women (n=24, mean age=22.4+/-1.8 years) were studied.

MEASUREMENTS AND RESULTS

The following sleep and sleep-related breathing measures showed significant increases in all four groups from baseline to occlusion: percentage of stage 1, number of transient arousals, transient arousal index, apnea index, respiratory disturbance index (RDI), and mean apnea length. No significant relationships were found between occlusion-night RDI and tonsillar size, cephalometric variables, or BMI, either singly or in combination.

CONCLUSIONS

Subjects' responses to nasal occlusion varied: most demonstrated a minimal and clinically insignificant increase in RDI; few showed a marked increase in RDI. Significant increases of sleep fragmentation -- even in the absence of frankly disturbed breathing -- indicate that nasal occlusion may secondarily affect waking function if prolonged over a series of nights.

Sleep, breathing, and cephalometrics in older children and young adults. Part I -- Normative values

STUDY OBJECTIVES

Aims were (1) to provide normative values for sleep and sleep-related breathing variables and physical features (cephalometrics, body mass index [BMI], and tonsillar size) in older children/adolescents and young adults, (2) to describe sex and age group differences, and (3) to evaluate relationships between physical features and sleep-related breathing variables.

DESIGN

Standard polysomnographic variables describing sleep and breathing were measured during a single night. Cephalometric measures were obtained from a standing lateral skull radiograph.

SUBJECTS

Normal, healthy boys (n=23; mean age=13.3+/-2.1 years), girls (n=22; mean age =13.8+/-1.8 years), men (n=23; mean age=22.2+/-1.5 years), and women (n=24; mean age=22.4+/-1.8 years) with BMI less than 27 were evaluated.

RESULTS

Sleep variables showed age group and sex differences consistent with published norms. Slow-wave sleep and rapid eye movement (REM) latency declined with age; transient arousals increased with age. Sleep-related breathing variables showed few changes related to age group or sex; small but statistically significant sex differences were found for arterial oxygen saturation nadir (lower in male subjects) and respiration disturbance index in non-REM sleep (greater in male subjects). Differences in cephalometric measures largely reflected normal growth and expected sex differences. No significant relationships between sleep-related breathing variables and physical findings were observed.

CONCLUSIONS

These data provide well-controlled normative values for sleep, breathing, and cephalometrics in a group of normal older children, adolescents, and young adults. The data provide useful reference points for patients of these ages in whom sleep apnea is suspected, particularly since such clinical studies are normally based on first-night polysomnography. Furthermore, these values represent developmentally appropriate grouping of the data.

Activity-based sleep-wake identification: an empirical test of methodological issues

The effects of actigraph placement and device sensitivity on actigraphic automatic sleep-wake scoring were assessed using concomitant polysomnographic and wrist actigraphic data from dominant and nondominant hands of 20 adults and 16 adolescents during 1 laboratory night. Although activity levels differed between dominant and nondominant wrists during periods of sleep (F = 4.57; p < 0.05) and wake (F = 15.5; p < 0.0005), resulting sleep-wake scoring algorithms were essentially the same and were equally explanatory (R2 = 0.64; p < 0.0001). When the sleep-wake scoring algorithm derived from the nondominant hand was used to score the nondominant data for sleep-wake, overall agreement rates with polysomnography scoring ranged between 91 and 93% for the calibration and validation samples. Results obtained with the same algorithm for the dominant-wrist data were within the same range. Agreement for sleep scoring was consistently higher than for wake scoring. Statistical manipulation of activity levels before applying the scoring algorithm indicated that this algorithm is quite robust toward moderate changes in activity level. Use of "twin-wrist actigraphy" enables identification of artifacts that may result from breathing-related motions.

Sleep-disordered breathing and behavior in three risk groups: preliminary findings from parental reports

Sleep-related breathing disorders may cause excessive daytime sleepiness, cognitive impairment, and behavior problems in children and adolescents. Adenotonsillar enlargement (AT) is known to be a significant risk factor for these disorders, which have also been reported in several patients with Down syndrome (DS). Children with attention deficit disorder/hyperactivity (ADD) show behavior problems that may be related to disturbed nocturnal sleep in some. To evaluate the relationships among these disorders and symptoms, parents of 29 school-aged children with AT, 70 with DS and 48 of their siblings (DS-SIB), and 21 with ADD completed a 20-item screening questionnaire covering nocturnal sleep symptoms and daytime behavior problems. Nocturnal symptoms of sleep-related breathing disorders--snoring, breathing pauses during sleep--were reported more commonly by parents of AT and DS children. However, parents of two of the ADD children reported significant signs of sleep-related breathing disorders. Daytime behavior problems were more common in ADD and AT than in the DS group. Bedwetting reports did not distinguish groups. Direct comparisons of DS and DS-SIB groups showed that more DS were mouth breathers, snored, stopped breathing at night, and were sleepy in the daytime. These findings underscore the importance of obtaining a history of nocturnal sleep from parents of children with AT and DS, as well as those with disrupted daytime behavior.

A self-administered rating scale for pubertal development

The purpose of this study was to assess the reliability and validity of a new self-rating scale to measure children's pubertal status without pictorial representations or interviews. The scale is an adaptation of an interview-based puberty-rating scale by Petersen, and included scores for each of five items rating physical development, an overall maturation measure, and a categorical maturation score designed to be similar to Tanner staging categories. Each measure was obtained from independent ratings by students and parents, and a 3-point categorical scale was also obtained from teachers. Subjects included 698 5th- and 6th-grade students (323 boys and 375 girls) from 61 schools and their parents and teachers. Fifth-grade students rated themselves and were rated by parents as less mature than 6th graders; 6th-grade girls were consistently rated more mature than boys of the same age. Significant correlations were found between parents and students for all of the measures for 6th-graders and 5th-grade girls and several measures for 5th-grade boys. This new scale is a useful tool for assessing pubertal status in settings that require noninvasive measures.

Association between puberty and delayed phase preference

Many teenagers go to bed and wake up significantly later than younger children, a developmental progression thought to reflect adolescent psychosocial processes. To determine whether biological processes may underlie a delay of phase preference in adolescents, 183 sixth-grade boys and 275 sixth-grade girls completed questionnaires for morningness/eveningness (M/E) and pubertal status. School environment and birth order were also evaluated. A significant relationship of pubertal status to M/E was found in girls, with a similar though nonsignificant trend in boys. No relationship between M/E and psychosocial factors was found. These data support involvement of a biological factor in the adolescent phase preference delay and indicate that our current understanding of adolescent sleep patterns may need revision.

Parental reports of seasonal mood and behavior changes in children

OBJECTIVE

The chief purpose of this study was to investigate the nature and prevalence of children's seasonal symptoms.

METHOD

Parental reports of seasonal changes in six mood or behavioral symptoms (sleeping, eating, irritability, energy, withdrawal, and sadness) were surveyed for children living across the United States. The sample included 892 girls (mean age = 10.5 +/- 1.0 years) and 788 boys (mean age = 10.6 +/- 0.9 years), with a response rate of 46% for girls' parents and 39% for boys' parents.

RESULTS

At least one winter recurring symptom was reported in 48.5% of children, as compared with 9.1% in fall and 10.8% in spring. Winter symptoms were reported equally in girls and boys with one exception ("is tired"); age effects were found for three symptoms only in girls ("sleep more," "is tired," and "withdraws"). Regional effects showed more winter symptoms reports in northern zones than in southern zones.

CONCLUSIONS

Given the potential therapeutic benefit of light therapy in children with such seasonal patterns, careful assessment of seasonality is merited for children with winter mood and behavior problems.

Evaluation of excessive daytime sleepiness

Measures for assessing daytime sleepiness can be categorized into four general types-behavioral observation, laboratory performance, introspection, and physiological techniques. Each approach has its advantages and disadvantages. Thus, for example, observational techniques may provide a minimally 'contaminated' sample, but inferences may be quite difficult; laboratory performance measures may indicate vulnerabilities associated with sleepiness, but may be limited because of practice effects; introspection provides a personal perspective, but that point of view may be influenced by past history or ability to articulate; physiological measures may provide the most 'objective measures', but are difficult to apply to field studies. The Multiple Sleep Latency Test (MSLT) is the most thoroughly studied physiological measure of sleepiness relying upon serial assessments of the speed of falling asleep in standard conditions intended to optimize the sleep onset process. Procedures for administering, analyzing, and interpreting the MSLT are presented.

Sleep-disordered breathing in patients with Duchenne muscular dystrophy using negative pressure ventilators

We studied the occurrence of nocturnal disordered breathing events and O2 desaturations in 12 patients with late-stage Duchenne muscular dystrophy (DMD) using negative pressure ventilators. We also assessed the effects of O2 supplementation and nasal continuous positive airway pressure (CPAP) on disordered breathing events in selected patients and examined sleep quality in a small subgroup. Average age was 23 + 2 years and FVC was 293 + 33 ml. Eleven of the 12 patients had more than five disordered breathing events per hour during nocturnal monitoring, and the lowest O2 saturation was < 85 percent in nine patients. Nasal O2 (2 L/min) during negative pressure ventilation in four patients did not alter the frequency of disordered breathing events, prolonged the mean and maximum durations of events, and failed to eliminate severe O2 desaturations in two patients. Nasal CPAP was used in two patients during negative pressure ventilation and completely eliminated disordered breathing events in both. Overnight polysomnography during negative pressure ventilation in three patients demonstrated frequent awakenings that fell in frequency following elective tracheostomy in two patients and use of nasal CPAP in one. We conclude that negative pressure ventilation in patients with late-stage DMD is associated with frequent disordered breathing events and severe O2 desaturations in many patients. Concomitant use of O2 supplementation may prolong the events, but a switch to positive pressure ventilation or addition of nasal CPAP is effective therapy.

Multiple sleep latency tests during the constant routine

The "post-lunch dip" is a common behavioral phenomenon, though perhaps a misnomer. Biphasic models of the human sleep tendency rhythm suggest an alternative explanation for the afternoon decline in alertness. Sleep tendency was measured with the Multiple Sleep Latency Test (MSLT) at 2-hour intervals in 16 volunteers from three age groups (ages 10-12, ages 16-17, ages 62-74 years) during a constant routine in which small meals were given each hour. Baseline scores showed no significant Time of Day effect, although a trend for an afternoon dip was present in the eldest group. During the constant routine, a significant Time of Day effect was found for the two older groups and not for the prepubertal group. The results indicate a midday increase in sleep tendency that is unrelated to food intake but that may be related to developmental or maturational processes.

Studies in the genetics of obstructive sleep apnea. Familial aggregation of symptoms associated with sleep-related breathing disturbances

Previous studies of single families have suggested that familial factors may be important in the pathogenesis of obstructive sleep apnea. In this report, the role of inheritance in obstructive sleep apnea was assessed by quantitating the degree of familial clustering of symptoms associated with sleep-related breathing disorders. In total, 272 subjects from 29 families identified through an index case with obstructive sleep apnea and 21 control families with no relative known to have sleep apnea were studied with questionnaires that ascertained health status and symptoms. The unadjusted odds ratios of habitual or disruptive snoring, breathing pauses, and excessive day-time sleepiness in subjects with a single relative with the same symptom were 1.40 to 1.53 (p less than 0.05). Odds ratios increased progressively for subjects with increasing numbers of symptomatic relatives). Adjustment for body mass index, age, and gender modestly reduced these odds ratios to 1.33 to 1.42. These data suggest a significant familial aggregation of symptoms associated with sleep-disordered breathing that appears independent of familial similarities in weight.

Interactions of sleep and clonidine on daytime prolactin secretion in humans

The suppressive roles of adrenergic stimulation and rapid eye movement (REM) sleep on human prolactin (PRL) secretion are controversial. We examined the effects of sleep, clonidine (an alpha 2-adrenergic agonist), and their interaction on PRL secretion. Two groups of normal men (nine each) were studied in two morning sessions. Each group received either placebo or clonidine in both sessions. Subjects remained awake in the first session and in the next session they were asked to sleep for 3 h after the test dose was given. Blood samples were drawn at 30-min intervals and polysomnographic recordings were obtained at each session. PRL concentrations remained at baseline and no clonidine effect was detected while awake. PRL concentrations increased in placebo and clonidine groups during sleep. Despite significant suppression of REM sleep in the clonidine group, no differences were detected between the placebo and clonidine groups in peak PRL or mean PRL concentrations during the study. Also, no significant difference was detected in comparing PRL responses during non-REM sleep in both groups. The results suggest that alpha 2-adrenergic stimulation does not have a significant role in modulating human PRL secretion during sleep.

MSLT-defined sleepiness and neuropsychological test performance do not correlate in the elderly

This study investigated whether a sensitive, physiological measure of alertness/sleepiness, the Multiple Sleep Latency Test (MSLT), was related to neuropsychological test performance in elderly individuals. We hypothesized that the greater likelihood of falling asleep during the daytime on the MSLT would be related to relatively poorer performances on a variety of neuropsychological tests. Results from a homogeneous sample of 35 relatively well-educated, high functioning, elderly community volunteers confirmed the presence of characteristic levels of daytime alertness which were stable within individuals (r = .70 to .73) and showed large variation across individuals (coefficients of variation: 54-84%). Despite this wide intersubject variability, MSLT-defined alertness/sleepiness was unrelated to neuropsychological test results. We discuss these results in terms of the performance deficits known to accompany sleepiness in experimental studies of sleep deprivation and in terms of the behavioral slowing known to occur in normal aging.

Sleepwalking precipitated by treatment of sleep apnea with nasal CPAP

A 33-year-old man with a long history of snoring, observed apneic episodes, and excessive daytime sleepiness, underwent all-night polysomnography, which demonstrated severe obstructive sleep apnea. During the nasal CPAP trial, two episodes of sleepwalking were observed during a period of delta sleep rebound.

Sleep, clonidine, and their interactive effect on growth hormone secretion in normal men

Central alpha 2-adrenergic function is often inferred from the growth hormone (GH) response to clonidine, despite the drug's known hypnotic effect and the accepted cholinergic mechanism for sleep-related GH secretion. We examined the effect of daytime sleep on GH secretion in normal men taking placebo or clonidine orally, using a two-group blind design (placebo, clonidine; n = 9 each). Each subject participated in two morning sessions monitored by polysomnography: wake (sleep actively prevented) and sleep (subjects asked to sleep for 3 hr after receiving placebo or clonidine). Blood samples were drawn at times -15 min, 0, and every 30 min for 3 hr after the test dose was given. The total sleep time was similar for both groups. The placebo/wake group had lower GH responses than the other three groups. None of the GH responses in the clonidine/sleep group were significantly different from those in the placebo/sleep group; and the peak GH micrograms/L, mean +/- SD) was 16.9 +/- 10.9 vs. 14.6 +/- 10.5, respectively. We conclude that the GH response to clonidine may not be indicative of alpha 2-adrenergic function if sleep is permitted during the test.

Sleepiness and nap sleep following a morning dose of clonidine

The effects of a single oral dose of clonidine on morning nap sleep and daytime sleepiness were evaluated in 18 normal young adult male volunteers aged 18-21 years. Polysomnography and subjective sleepiness (Stanford Sleepiness Scale and linear analog sleepiness rating scale) measures were obtained on 2 mornings. Half the subjects received placebo and half clonidine (0.25-0.3 mg) on both occasions. Subjects were instructed to stay awake on the first morning (wake) and to sleep on the second (sleep). Efforts were made to help subjects maintain arousal on the wake day. Results from the wake morning showed that clonidine subjects were significantly sleepier than placebo subjects as measured by introspection. In addition, clonidine subjects tended to have more polysomnographic signs of sleepiness (microsleeps) when not actively aroused. On the sleep morning, clonidine and placebo subjects slept for approximately 90% of the 3-h nap. Stage 1 and rapid-eye-movement (REM) sleep were significantly reduced and stage 2 sleep significantly increased in the clonidine group. In conclusion, a morning dose of clonidine produced profound sedation in waking subjects and marked REM suppression in sleeping subjects.

Nightly variation of periodic leg movements in sleep in middle aged and elderly individuals

This study investigated night-to-night variation in periodic leg movements in sleep (PLMS). PLMS are common in the elderly, but their mechanism and significance are not understood. Forty-five aged individuals (means = 69.7 years) were studied polysomnographically for 2 or 3 nights with surface electrodes placed above the anterior tibialis. Results indicated that PLMS varied considerably from night to night within individuals, though there was not a significant difference between nights for the entire group. Some evidence indicated that individuals with less severe sleep complaints showed greater nightly variation. The nightly variation in PLMS was over four times as large as the nightly variation in breathing disturbance in sleep, another condition common in the sleep of the aged. These data suggest that studies relating PLMS to other key variables (e.g. symptoms of disturbed sleep) should rely on multiple nights of data or, if single night data are used, be particularly careful to replicate findings across samples.

Daytime sleepiness: quantification of a behavioral state

A neurophysiological technique that quantifies drowsiness as the speed of falling asleep at intervals across a day is used to identify patterns of sleepiness/alertness. The Multiple Sleep Latency Test (MSLT) reveals a daily biphasic organization of sleepiness that is affected in predictable ways by the length and continuity of nocturnal sleep on one or several nights, and by maturation, aging, sleep pathology, and drug ingestion. The systematic nature of these relationships provides impetus to efforts examining the neurobiological mechanisms subserving the delicate balance of sleep and wakefulness.