Sleep Validity of a Non-Contact Bedside Movement and Respiration-Sensing Device.

STUDY OBJECTIVES: To assess the sleep detection and staging validity of a non-contact, commercially available bedside bio-motion sensing device (S+, ResMed) and evaluate the impact of algorithm updates. METHODS: Polysomnography data from 27 healthy adult participants was compared epoch-by-epoch to synchronized data that were recorded and staged by actigraphy and S+. An update to the S+ algorithm (common in the rapidly evolving commercial sleep tracker industry) permitted comparison of the original (S+V1) and updated (S+V2) versions. RESULTS: Sleep detection accuracy by S+V1 (93.3%), S+V2 (93.8%), and actigraphy (96.0%) was high; wake detection accuracy by each (69.6%, 73.1%, and 47.9%, respectively) was low. Higher overall S+ specificity, compared to actigraphy, was driven by higher accuracy in detecting wake before sleep onset (WBSO), which differed between S+V2 (90.4%) and actigraphy (46.5%). Stage detection accuracy by the S+ did not exceed 67.6% (for stage N2 sleep, by S+V2) for any stage. Performance is compared to previously established variance in polysomnography scored by humans: a performance standard which commercial devices should ideally strive to reach. CONCLUSIONS: Similar limitations in detecting wake after sleep onset (WASO) were found for the S+ as have been previously reported for actigraphy and other commercial sleep tracking devices. S+ WBSO detection was higher than actigraphy, and S+V2 algorithm further improved WASO accuracy. Researchers and clinicians should remain aware of the potential for algorithm updates to impact validity. COMMENTARY: A commentary on this article appears in this issue on page 935.

Sleep: A Pathway Linking Personality to Mortality Risk.

Personality and sleep predict longevity; however, no investigation has tested whether sleep mediates this association. Thus, we tested this effect across a 20-year follow-up (N = 3,759) in the Midlife Development in the United States cohort (baseline M age = 47.15) using proportional hazards in a structural equation modeling framework. Lower conscientiousness predicted increased death risk via the direct, indirect, and total effect of quadratic sleep duration. Although there were no other direct personality-mortality effects, higher neuroticism and agreeableness and lower conscientiousness predicted increased death risk via the joint indirect effects of quadratic sleep duration and higher daytime dysfunction. Lower extraversion predicted increased mortality risk via the indirect effect of daytime dysfunction. Our findings have implications for personality-based health interventions.

Long-term effects of pregnancy and childbirth on sleep satisfaction and duration of first-time and experienced mothers and fathers.

STUDY OBJECTIVES: To examine the changes in mothers' and fathers' sleep satisfaction and sleep duration across prepregnancy, pregnancy, and the postpartum period of up to 6 years after birth; it also sought to determine potential protective and risk factors for sleep during that time. METHODS: Participants in a large population-representative panel study from Germany reported sleep satisfaction and sleep duration in yearly interviews. During the observation period (2008-2015), 2541 women and 2118 men reported the birth of their first, second, or third child and provided longitudinal data for analysis. Fixed-effects regression models were used to analyze changes in sleep associated with childbirth. RESULTS: Sleep satisfaction and duration sharply declined with childbirth and reached a nadir during the first 3 months postpartum, with women more strongly affected (sleep satisfaction reduction compared with prepregnancy: women, 1.81 points on a 0 to 10 scale, d = 0.79 vs. men, 0.37 points, d = 0.16; sleep duration reduction compared with prepregnancy: women, 62 min, d = 0.90 vs. men, 13 min, d = 0.19). In both women and men, sleep satisfaction and duration did not fully recover for up to 6 years after the birth of their first child. Breastfeeding was associated with a slight decrease in maternal sleep satisfaction (0.72 points, d = 0.32) and duration (14 min, d = 0.21). Parental age, household income, and dual vs. single parenting were unrelated, or only very weakly related, to improved sleep. CONCLUSIONS: Following the sharp decline in sleep satisfaction and duration in the first months postpartum, neither mothers' nor fathers' sleep fully recovers to prepregnancy levels up to 6 years after the birth of their first child.

Beyond the Bayley: Neurocognitive Assessments of Development During Infancy and Toddlerhood.

The use of global, standardized instruments is conventional among clinicians and researchers interested in assessing neurocognitive development. Exclusively relying on these tests for evaluating effects may underestimate or miss specific effects on early cognition. The goal of this review is to identify alternative measures for possible inclusion in future clinical trials and interventions evaluating early neurocognitive development. The domains included for consideration are attention, memory, executive function, language, and socioemotional development. Although domain-based tests are limited, as psychometric properties have not yet been well-established, this review includes tasks and paradigms that have been reliably used across various developmental psychology laboratories.

Breastfeeding Duration Is Associated with Regional, but Not Global, Differences in White Matter Tracts.

Extended breastfeeding through infancy confers benefits on neurocognitive performance and intelligence tests, though few have examined the biological basis of these effects. To investigate correlations with breastfeeding, we examined the major white matter tracts in 4-8 year-old children using diffusion tensor imaging and volumetric measurements of the corpus callosum. We found a significant correlation between the duration of infant breastfeeding and fractional anisotropy scores in left-lateralized white matter tracts, including the left superior longitudinal fasciculus and left angular bundle, which is indicative of greater intrahemispheric connectivity. However, in contrast to expectations from earlier studies, no correlations were observed with corpus callosum size, and thus no correlations were observed when using such measures of global interhemispheric white matter connectivity development. These findings suggest a complex but significant positive association between breastfeeding duration and white matter connectivity, including in pathways known to be functionally relevant for reading and language development.

Digital Media and Sleep in Childhood and Adolescence.

Given the pervasive use of screen-based media and the high prevalence of insufficient sleep among American youth and teenagers, this brief report summarizes the literature on electronic media and sleep and provides research recommendations. Recent systematic reviews of the literature reveal that the vast majority of studies find an adverse association between screen-based media consumption and sleep health, primarily via delayed bedtimes and reduced total sleep duration. The underlying mechanisms of these associations likely include the following: (1) time displacement (ie, time spent on screens replaces time spent sleeping and other activities); (2) psychological stimulation based on media content; and (3) the effects of light emitted from devices on circadian timing, sleep physiology, and alertness. Much of our current understanding of these processes, however, is limited by cross-sectional, observational, and self-reported data. Further experimental and observational research is needed to elucidate how the digital revolution is altering sleep and circadian rhythms across development (infancy to adulthood) as pathways to poor health, learning, and safety outcomes (eg, obesity, depression, risk-taking).

Effects of a single night of postpartum sleep on childless women's daytime functioning.

STUDY OBJECTIVES: The maternal postpartum period is characterized by sleep fragmentation, which is associated with daytime impairment, mental health disturbances, and changes in melatonin patterns. In addition to sleep fragmentation, women undergo a complex set of physiological and environmental changes upon entering the postpartum period, confounding our understanding of effects of postpartum sleep disturbance. The primary study aim was to understand the basic impact of a single night of postpartum-like sleep fragmentation on sleep architecture, nocturnal melatonin levels, mood, daytime sleepiness, and neurobehavioral performance. MEASUREMENTS AND RESULTS: For one week prior to entry into the laboratory, eleven healthy nulliparous women kept a stable sleep-wake schedule (verified via actigraphy). Participants contributed three consecutive nights of laboratory overnight polysomnography: (1) a habituation/sleep disorder screening night; (2) a baseline night; and (3) a sleep fragmentation night, when participants were awakened three times for ~30min each. Self-reported sleep quality and mood (Profile of Mood States survey) both decreased significantly after sleep fragmentation compared to baseline measurements. Unexpectedly, daytime sleepiness (Multiple Sleep Latency Test) decreased significantly after sleep fragmentation. Experimental fragmentation had no significant effect on time spent in nocturnal sleep stages, urinary 6-sulfatoxymelatonin concentration, or psychomotor vigilance test performance. Participants continued to provide actigraphy data, and daily PVTs and self-reported sleep quality assessments at home for one week following sleep fragmentation; these assessments did not differ from baseline values. CONCLUSIONS: While there were no changes in measured physiological components of a single night of postpartum-like experimental sleep fragmentation, there were decreases in self-reported measures of mood and sleep quality. Future research should examine the effects of multiple nights of modeling postpartum-like sleep fragmentation on objective measures of sleep and daytime functioning.

What are postpartum women doing while the rest of the world is asleep?

Large individual differences characterize maternal postpartum sleep and adjustment. Our goal was to explore aspects of mothers' nocturnal environments and behaviours that may explain differences in postpartum adjustment. A total of 201 mothers of infants aged 0-6 months completed an online survey with demographics, number and duration of nocturnal awakenings, caretaking behaviours, environment and nocturnal activities during 'one typical night during the past week'. Mothers reported 2.9 [standard deviation (SD) ± 1.7] nocturnal awakenings, each lasting 33.9 (SD ± 22.5) min. Infant age was related inversely to duration but unrelated to number of awakenings. Falling asleep while feeding was less frequent among exclusively formula-feeders. Among the entire sample, mothers used a cellphone (59%), backlit tablet (25%), TV (20%) and computer (16%) during nocturnal awakenings. Watching TV and using a computer were each associated with longer nocturnal awakenings. Eighty-nine per cent of women used ≥1 extra light source during nocturnal awakenings: night light (35%), light from a cracked door (28%), desk lamp (25%), electronic device (19%) or room light (14%). Light source(s) was unrelated to number or duration of nocturnal awakenings. These data suggest that, although supplemental light sources were not associated with awakenings, TV and computer use accounted for longer awakenings. Feeding method and technology use may help to explain individual differences in postpartum adjustments and may be targets for more effective interventions.

Diurnal fatigue patterns, sleep timing, and mental health outcomes among healthy postpartum women.

Postpartum women have frequently interrupted sleep, report high levels of fatigue, and may experience circadian rhythm disruptions. They are also susceptible to mood impairments, anxiety, and stress. The current study explored associations between maternal postpartum daily fatigue patterns, which should vary according to circadian influences and mental health. Seventy-one primiparous, healthy mothers completed multiple daily self-reports of fatigue during postpartum Weeks 2 and 12 and were categorized at each week as having either a rhythmic or random fatigue pattern during the daytime. Wrist actigraphy data were used to calculate sleep midpoints. Surveys assessed chronotype, mood, anxiety, and stress. At postpartum Week 2, there were no differences in mental health measures between fatigue groups. At postpartum Week 12, higher overall fatigue levels were associated with increased anxiety, stress, and mood disruption. However, overall fatigue levels did not differ between fatigue groups. Women with a rhythmic fatigue pattern reported significantly less stress and more vigor than women with a random fatigue pattern. An earlier sleep midpoint was associated with a rhythmic fatigue pattern during postpartum Week 12. These data suggest that, despite similar average daily fatigue levels, having a rhythmic daily pattern of fatigue may be advantageous for mental health outcomes among postpartum women.

A mixed-method examination of maternal and paternal nocturnal caregiving.

OBJECTIVES: The study objectives were to describe and compare causes of, and activities during, postpartum parents' nocturnal awakenings. METHODS: Twenty-one primiparous postpartum couples were studied for 1 week with qualitative and quantitative methods. RESULTS: Mothers reported more awakenings per night (3.3 ± 1.1) and more wake time after going to sleep (116.0 ± 60.0 minutes) compared to fathers (2.4 ± 0.5 and 42.7 ± 39.4 minutes, respectively). "Actions taken" during maternal nocturnal awakenings were primarily for infant feeding (49.0%), general infant care (18.5%), and infant changing (12.0%). "Actions taken" during paternal nocturnal awakenings were primarily "passive awakenings" (35.9%), for self-care (18.4%), and for infant feeding (9.4%). CONCLUSIONS: Qualitative analyses revealed ways that new families can optimize the sleep of both parents while also providing optimal nocturnal infant care.

Respiratory and polysomnographic values in 3- to 5-year-old normal children at higher altitude.

STUDY OBJECTIVES: To determine polysomnographic parameter differences in children living at higher altitude to children living near sea level. DESIGN AND SETTING: Prospective study of non-snoring, normal children recruited from various communities around Denver, CO. In-lab, overnight polysomnograms were performed at a tertiary care children's hospital. All children required residence for greater than one year at an elevation around 1,600 meters. PARTICIPANTS: 45 children (62% female), aged 3-5 years, 88.9% non-Hispanic white with average BMI percentile for age of 47.8% ± 30.7%. MEASUREMENTS AND RESULTS: Standard sleep indices were obtained and compared to previously published normative values in a similar population living near sea level (SLG). In the altitude group (AG), the apnea-hypopnea index was 1.8 ± 1.2 and the central apnea-hypopnea index was 1.7 ± 1.1, as compared to 0.9 ± 0.8 and 0.8 ± 0.7, respectively, (P ≤ 0.005) in SLG. Mean end-tidal CO2 level in AG was 42.3 ± 3.0 mm Hg and 40.6 ± 4.6 mm Hg in SLG (P = 0.049). The ≥ 4% desaturation index was 3.9 ± 2.0 in AG compared to 0.3 ± 0.4 in SLG (P < 0.001). Mean periodic limb movement in series index was 10.1 ± 12.3 in AG and 3.6 ± 5.4 in SLG (P = 0.001). CONCLUSION: Comparison of altitude and sea level sleep studies in healthy children reveals significant differences in central apnea, apneahypopnea, desaturation, and periodic limb movement in series indices. Clinical providers should be aware of these differences when interpreting sleep studies and incorporate altitude-adjusted normative values in therapeutic-decision making algorithms.

Timing and variability of postpartum sleep in relation to daytime performance.

Postpartum women have highly disturbed sleep, also known as sleep fragmentation. Fragmentation extends their total sleep period, also disrupting sleep timing. A stable and earlier sleep period among non-postpartum populations is related to better performance, physical health, and mental health. However, sleep timing has not been examined among postpartum women who are also vulnerable to daytime impairment. The study objective was to examine how the timing and regularity of sleep during the early postpartum period are related to daytime functioning across postpartum weeks 2-13. In this field-based study, 71 primiparous women wore an actigraph, a small wrist-worn device that monitors sleep and sleep timing, for the 12-week study period. Mothers self-administered a 5-min psychomotor vigilance test (PVT) each morning to evaluate the number of >500ms response lapses. They also completed a Morningness-Eveningness scale at the beginning of the study to identify chronotype. After controlling for maternal age, earlier sleep timing was associated with significantly fewer PVT lapses at postpartum weeks 9,12; a more stable sleep midpoint was associated with significantly fewer PVT lapses at postpartum weeks 2,5-13. Earlier sleep midpoints were related to more stable sleep midpoints at postpartum week 2 and a morning-type chronotype. An earlier sleep midpoint was also associated with a reduced slope of worsening PVT lapses across weeks. Across the first 12 postpartum weeks, women with earlier or more stable sleep periods had less daytime impairment than women with later or more variable sleep midpoints. Postpartum women with earlier sleep midpoints also showed less severe decrements in performance across time, which has been attributed to cumulative impacts of sleep disturbance. These data suggest that the sleep period, in addition to sleep duration and fragmentation, should be more closely examined, particularly among vulnerable women, as it may affect the neurobehavioral performance of new mothers.

Minimum duration of actigraphy-defined nocturnal awakenings necessary for morning recall.

BACKGROUND: Healthy adults awaken between each sleep cycle approximately 5 times each night but generally do not remember all of these awakenings in the morning. A rule of thumb has arisen in the sleep field that approximately 5 min of continuous wakefulness are required to form a memory for an awakening. However, few studies have examined memory for these sleep-wake transitions and none have done so in the home, while participants follow their normal routine. METHODS: Self-report and actigraphy were used in the participant's home environment to determine the minimum duration of an awakening necessary for morning recall for each of the 39 healthy adults. RESULTS: Recall thresholds ranged from 30 to 600 s with a mean of 259 s (4 min 19 s) and were negatively associated with sleep efficiency but not significantly associated with total sleep time, age, income, or education. There also was a sex by cohabitation interaction, with single men having lower thresholds than single women and cohabiting participants, which was explained by higher sleep efficiency in noncohabitating men. Large individual differences suggest that many factors may influence recall threshold. CONCLUSIONS: Our preliminary study is the first to calculate the duration of wakefulness necessary for morning recall of nocturnal awakenings and the first to use a field-based design, allowing for the study of habitual sleep patterns at the participant's home. Further study is needed to explore if recall thresholds calculated using actigraphy can be validated against polysomnography (PSG) or be used to guide potential treatments.

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.

Sleep and sleepiness among first-time postpartum parents: a field- and laboratory-based multimethod assessment.

The study aim was to compare sleep, sleepiness, fatigue, and neurobehavioral performance among first-time mothers and fathers during their early postpartum period. Participants were 21 first-time postpartum mother-father dyads (N = 42) and seven childless control dyads (N = 14). Within their natural environment, participants completed 1 week of wrist actigraphy monitoring, along with multi-day self-administered sleepiness, fatigue, and neurobehavioral performance measures. The assessment week was followed by an objective laboratory-based test of sleepiness. Mothers obtained more sleep compared to fathers, but mothers' sleep was more disturbed by awakenings. Fathers had greater objectively measured sleepiness than mothers. Mothers and fathers did not differ on subjectively measured sleep quality, sleepiness, or fatigue; however, mothers had worse neurobehavioral performance than fathers. Compared to control dyads, postpartum parents experienced greater sleep disturbance, sleepiness, and sleepiness-associated impairments. Study results can inform social policy, postpartum sleep intervention development, and research on postpartum family systems and mechanisms that propagate sleepiness.

Community based study of sleep bruxism during early childhood.

OBJECTIVES: The aims for this study were to determine the prevalence of sleep-bruxism among young children, explore child behavior problems that may be associated with sleep-bruxism, and identify relations among sleep-bruxism, health problems, and neurocognitive performance. METHODS: The current study was a retrospective analysis of parent report surveys, and behavioral and neurocognitive assessments. Parents of 1953 preschool and 2888 first grade children indicated their child's frequency of bruxism during sleep. A subsample of preschool children (n=249) had additional behavioral, as well as neurocognitive assessments. Among the subsample, parents also reported on their child's health, and completed the Child Behavioral Checklist; children were administered the Differential Ability Scales, and Pre-Reading Abilities subtests of the Developmental Neuropsychological Assessment. RESULTS: 36.8% of preschoolers and 49.6% of first graders were reported to brux ⩾1time per week. Among the preschool subsample, bruxing was independently associated with increased internalizing behaviors (ß=.17). Bruxism was also associated with increased health problems (ß=.19), and increased health problems were associated with decreased neurocognitive performance (ß=.22). CONCLUSIONS: The prevalence of sleep-bruxism was high. A dynamic and potentially clinically relevant relation exists among sleep-bruxism, internalizing behaviors, health, and neurocognition. Pediatric sleep-bruxism may serve as a sentinel marker for possible adverse health conditions, and signal a need for early intervention. These results support the need for an interdisciplinary approach to pediatric sleep medicine, dentistry, and psychology.

Use of actigraphy for assessment in pediatric sleep research.

The use of actigraphs, or ambulatory devices that estimate sleep-wake patterns from activity levels, has become common in pediatric research. Actigraphy provides a more objective measure than parent-report, and has gained popularity due to its ability to measure sleep-wake patterns for extended periods of time in the child's natural environment. The purpose of this review is: 1) to provide comprehensive information on the historic and current uses of actigraphy in pediatric sleep research; 2) to review how actigraphy has been validated among pediatric populations; and 3) offer recommendations for methodological areas that should be included in all studies that utilize actigraphy, including the definition and scoring of variables commonly reported. The poor specificity to detect wake after sleep onset was consistently noted across devices and age groups, thus raising concerns about what is an "acceptable" level of specificity for actigraphy. Other notable findings from this review include the lack of standard scoring rules or variable definitions. Suggestions for the use and reporting of actigraphy in pediatric research are provided.

Movement toward a novel activity monitoring device.

PURPOSE: Although 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). METHODS: To 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. RESULTS: Fitbit 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. CONCLUSIONS: The 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.

Perception of partner sleep and mood: postpartum couples' relationship satisfaction.

Separate research areas indicate that sleep quality, mood, and relationship satisfaction decline among couples during the postpartum period. Furthermore, accurate partner perceptions are associated with positive relationship qualities. In this study, 21 first-time postpartum mother-father dyads, contributed 1 week of continuous wrist actigraphy along with concurrent subjective Palm Pilot monitoring to provide objective and subjective sleep measures. Parents also reported on their own as well as their perception of their partners' sleep, mood, and relationship satisfaction. Greater objectively measured total sleep time was associated with greater relationship satisfaction. Mothers (a) underestimated fathers' self-reported frequency of nocturnal awakenings, as well as (b) relationship satisfaction, and (c) overestimated fathers' self-reported sleep quality. Fathers (a) underestimated mothers' self-reported duration of wake at night, as well as (b) sleep quality, and (c) overestimated mothers' self-reported mood disturbance. Preventative measures that target sleep and improvement in perception of partner's experiences could be used to buffer against decreases in relationship satisfaction among new parents.