Actigraphy-based sleep estimation in adolescents and adults: a comparison with polysomnography using two scoring algorithms

Objective Assessment of Sleep Patterns among Night-Shift Workers: A Scoping Review

In this scoping review of the literature, we identified the types and the parameters of objective measurements to assess sleep patterns among night-shift workers. We conducted a literature search using electronic databases for studies published from 1991 to 2020 and charted and summarized key information. We included 32 studies in the review. Polysomnography was used in 6 studies and wearable sleep detection devices were utilized in 26 studies. The duration of sleep assessment using the wearable devices ranged from 1 day to ≥4 weeks, and more than half of the studies collected data for >2 weeks. The majority of the studies used subjective questionnaires, such as the Karolinska Sleepiness Scale, Epworth Sleepiness Scale, and Pittsburgh Sleep Quality Index, in addition to objective sleep measurements. Total sleep time was the most common parameter, followed by sleep efficiency, sleep onset latency, and time or frequency of being awake. As the utilization of wearable devices to assess the sleep patterns of night-shift workers is expected to increase, further evaluation of device accuracy and precision, optimal data collection period, and key parameters is warranted.

The Impact of Television, Electronic Games, and Social Technology Use on Sleep and Health in Adolescents with an Evening Circadian Preference

There are mixed findings when examining if technology use is harmful for adolescent sleep and health. This study builds on these mixed findings by examining the association between technology use with sleep and health in a high-risk group of adolescents. Adolescents with an evening circadian preference (N = 176; 58% female, mean age = 14.77, age range = 10-18) completed measures over one week. Sleep was measured via actigraphy. Technology use and health were measured using ecological momentary assessment. Technology use was associated with an increase in sleep onset latency; with better emotional, social, cognitive, and physical health; and with worse behavioral health. This study offers support for technology use having some benefits and expands research on technology use to adolescents with an evening circadian preference.

Sleep affects the motor memory of basketball shooting skills in young amateurs

Sleep has long been shown as important for memory processing and retention, and has recently been implicated in motor memory consolidation. However, it is not known whether sports skills, including basketball shooting skills, are also affected by sleep in young, healthy individuals. Therefore, we investigated whether sleep before and after basketball shooting skill training affected the acquisition and retention of shooting skills. This study included 19 healthy male subjects who participated in a basketball shooting skill training session (100 shots) and a retention test performed 2 days later (30 shots). The learning and retention indices were calculated using performance scores that evaluated each subject's shooting skills. A wearable activity tracker was used to measure sleep parameters for 4 consecutive days, 2 days before and 2 days after training. We discovered the relationship between sleep duration before and after training and retention of shooting skills (sleep duration before training; p = 0.044, r = 0.467, sleep duration after training; p = 0.006, r = 0.606). The retention index for the subgroup with long sleep duration before and after training was significantly higher than that for the subgroup with short sleep duration before and after training, respectively (p = 0.021 for both). There was no significant relationship between learning index and each sleep parameter. Our results demonstrated that sleep duration before and after training was related to retention of shooting skills following basketball shooting skills training.

Daily coping moderates the relations between stress and actigraphic sleep: a daily intensive longitudinal study with ecological momentary assessments

BACKGROUND

Theoretical models argue that coping reduces stress responses, yet no studies have tested whether coping moderates the prospective stress effects on sleep in daily life.

PURPOSE

This study tested if coping moderates the stress-sleep association using a daily, intensive longitudinal design across 7-12 days.

METHODS

326 young adults (M_age = 23.24 ± 5.46) reported perceived stress and coping (problem-focused, emotional-approach, and avoidance) every evening between 20:00-02:00, providing over 2400 nights of sleep data and 3000 stress surveys from all participants. Actigraphy and sleep diaries measured total-sleep-time and sleep efficiency. Multilevel models tested the interaction effects of within- and between-person stress and coping on sleep.

RESULTS

Within-person problem-focused and emotional-approach coping moderated the within-person stress effects on actigraphic total-sleep-time (both p = 0.02); higher stress predicted shorter total-sleep-time only during high use of problem-focused or emotional-approach coping (both p = 0.01). Between-person avoidance moderated the between-person stress effect on actigraphic total-sleep-time (p = 0.04); higher stress predicted shorter total-sleep-time for high avoidance coping (p = 0.02). Within-person emotional-approach coping buffered the between-person stress effect on actigraphic sleep efficiency (p = 0.02); higher stress predicted higher sleep efficiency for high emotional-approach coping (p = 0.04).

CONCLUSIONS

This study showed that daily coping moderates the effects of evening stress on sleep that night. More efforts to cope with stress before bedtime had a short-term cost of shorter sleep that night. However, high use of emotional-approach coping buffered the impact of stress to promote sleep efficiency.

Past, Present, and Future of Multisensory Wearable Technology to Monitor Sleep and Circadian Rhythms

Movement-based sleep-wake detection devices (i.e., actigraphy devices) were first developed in the early 1970s and have repeatedly been validated against polysomnography, which is considered the “gold-standard” of sleep measurement. Indeed, they have become important tools for objectively inferring sleep in free-living conditions. Standard actigraphy devices are rooted in accelerometry to measure movement and make predictions, via scoring algorithms, as to whether the wearer is in a state of wakefulness or sleep. Two important developments have become incorporated in newer devices. First, additional sensors, including measures of heart rate and heart rate variability and higher resolution movement sensing through triaxial accelerometers, have been introduced to improve upon traditional, movement-based scoring algorithms. Second, these devices have transcended scientific utility and are now being manufactured and distributed to the general public. This review will provide an overview of: (1) the history of actigraphic sleep measurement, (2) the physiological underpinnings of heart rate and heart rate variability measurement in wearables, (3) the refinement and validation of both standard actigraphy and newer, multisensory devices for real-world sleep-wake detection, (4) the practical applications of actigraphy, (5) important limitations of actigraphic measurement, and lastly (6) future directions within the field.

Associations between brain structure and sleep patterns across adolescent development

STUDY OBJECTIVES

Structural brain maturation and sleep are complex processes that exhibit significant changes over adolescence and are linked to many physical and mental health outcomes. We investigated whether sleep-gray matter relationships are developmentally invariant (i.e. stable across age) or developmentally specific (i.e. only present during discrete time windows) from late childhood through young adulthood.

METHODS

We constructed the Neuroimaging and Pediatric Sleep Databank from eight research studies conducted at the University of Pittsburgh (2009-2020). Participants completed a T1-weighted structural MRI scan (sMRI) and 5-7 days of wrist actigraphy to assess naturalistic sleep. The final analytic sample consisted of 225 participants without current psychiatric diagnoses (9-25 years). We extracted cortical thickness and subcortical volumes from sMRI. Sleep patterns (duration, timing, continuity, regularity) were estimated from wrist actigraphy. Using regularized regression, we examined cross-sectional associations between sMRI measures and sleep patterns, as well as the effects of age, sex, and their interaction with sMRI measures on sleep.

RESULTS

Shorter sleep duration, later sleep timing, and poorer sleep continuity were associated with thinner cortex and altered subcortical volumes in diverse brain regions across adolescence. In a discrete subset of regions (e.g. posterior cingulate), thinner cortex was associated with these sleep patterns from late childhood through early-to-mid adolescence but not in late adolescence and young adulthood.

CONCLUSIONS

In childhood and adolescence, developmentally invariant and developmentally specific associations exist between sleep patterns and gray matter structure, across brain regions linked to sensory, cognitive, and emotional processes. Sleep intervention during specific developmental periods could potentially promote healthier neurodevelopmental outcomes.

Light Enhanced Cognitive Behavioral Therapy (CBT-I+Light) for Insomnia and Fatigue During Chemotherapy for Breast Cancer: A Randomized Controlled Trial

STUDY OBJECTIVES

Sleep problems are common during chemotherapy for breast cancer (BC). We evaluated whether combined brief cognitive behavioral and bright light therapy (CBT-I+Light) is superior to treatment as usual with relaxation audio (TAU+) for insomnia symptoms and sleep efficiency (primary outcomes).

METHODS

We randomized women receiving intravenous chemotherapy, stratified by tumor stage and insomnia severity index (ISI), to 6-weeks CBT-I+Light or TAU+. CBT-I+Light included one in-person session, one telephone call, seven emails, and 20 minutes bright light each morning. TAU+ comprised usual treatment and two emails with relaxation audio tracks. Patient-reported outcomes were assessed at baseline, midpoint (week 3), post (week 6) and 3-month follow-up.

RESULTS

Women (N = 101) were randomly assigned to CBT-I+Light or TAU+. The CBT-I+Light group showed significantly greater improvement in insomnia symptoms than the TAU+ group (-5.06 vs -1.93, P = .009; between-group effect size [ES] = .69). At 3-month follow-up, both groups were lower than baseline but did not differ from each other (between-group ES = .18, P = .56). CBT-I+Light had higher patient-reported sleep efficiency than TAU+ immediately after the start of intervention (P = .05) and significantly greater improvement in fatigue (between-group ES = .59, P = .013) and daytime sleep-related impairment (between-group ES = .61, P = .009) than the TAU+ group.

CONCLUSION

CBT-I+Light had a clinically significant impact on insomnia and fatigue with moderate effect sizes. Results support offering cognitive behavioral therapy for insomnia and bright light therapy during chemotherapy for breast cancer to help manage sleep and fatigue.

Intermittent Fasting and Sleep: A Review of Human Trials

This review examines the effects of two popular intermittent fasting regimens on sleep in adults with overweight and obesity. Specifically, the effects of time restricted eating (TRE; eating all food within a 4-10 h window) and alternate day fasting (ADF; 600 kcal fast day alternated with ad libitum feast day) on sleep quality, sleep duration, sleep latency, sleep efficiency, insomnia severity, and risk of obstructive sleep apnea, will be summarized. The role of weight loss will also be discussed. Results from our review reveal that the majority of these trials produced weight loss in the range of 1-6% from baseline. Sleep quality and sleep duration remained unaltered with TRE and ADF, as assessed by the Pittsburgh Sleep Quality Index (PSQI). The effects of intermittent fasting on sleep latency and sleep efficiency are mixed, with one study showing worsening of these parameters, and others showing no effect. Insomnia severity and the risk of obstructive sleep apnea remained unchanged in the trials assessing these metrics. Taken together, these preliminary findings suggest that TRE and ADF produce mild to moderate weight loss (1-6%) but their effects on sleep remain unclear. Solid conclusions are difficult to establish since participants in the studies had healthy sleep durations and no clinical insomnia at baseline, leaving little room for improvement in these metrics. Moreover, none of the trials were adequately powered to detect statistically significant changes in any measure of sleep. Future well-powered trials, conducted in individuals with diagnosed sleep disturbances, will be necessary to elucidate the effect of these popular diets on sleep.

Association of job strain with accelerometer-based sleep duration and timing of sleep among older employees

Job strain has been associated with poor sleep quality and could lead to changes in duration and timing of sleep as well. This study examined the association of job strain with sleep duration, bedtimes and awakening times among public sector employees close to their retirement age. Differences in these sleep parameters between workdays and free days across job strain groups were examined. Duration and timing of sleep were measured repeatedly with accelerometers among 466 public sector employees in Finland (mean age 63 years, 86% women), who contributed to 759 measurements in total. Job demands (low/high) and control (low/high) measured by self-reports and job exposure matrix were used to identify low strain (low demand, high control), passive (low, low), active (high, high) and high strain (high, low) jobs. No differences in sleep duration were observed on workdays, whereas on free days those in the high strain group had longer sleep duration than those in the low strain and passive job groups. The high strain group also extended their sleep from workdays to free days more, the extension being on average 59 min (95% CI 42 min-75 min) when adjusted for several sociodemographic, work and health factors. This extension of sleep duration resulted mostly from a greater delay of awakening times from workdays to free days. Psychosocial work factors, such as job strain, need to be considered when promoting sufficient sleep duration among older employees, as those with job strain may have a greater need for recovery and sleep.

On the Unification of Common Actigraphic Data Scoring Algorithms

Actigraphy is a well-known, inexpensive method to investigate human movement patterns. Sleep and circadian rhythm studies are among the most popular applications of actigraphy. In this study, we investigate seven common sleep-wake scoring algorithms designed for actigraphic data, namely Cole-Kripke algorithm, two versions of Sadeh algorithm, Sazonov algorithm, Webster algorithm, UCSD algorithm and Scripps Clinic algorithm. We propose a unified mathematical framework describing five of them. One of the observed novelties is that five of these algorithms are in fact equivalent to low-pass FIR filters with very similar characteristics. We also provide explanations about the role of some factors defining these algorithms, as none were given by their Authors who followed empirical procedures. Proposed framework provides a robust mathematical description of discussed algorithms, which for the first time allows one to fully understand their operation and basics.

The Assessment of Sleep Quality in Patients Following Valve Repair and Valve Replacement for Infective Endocarditis: A Retrospective Study at a Single Center

Background

The aim of this study was to measure sleep quality among patients who underwent infective endocarditis (IE) surgery and identify the risk factors involved in sleep disorders.

Material/Methods

In this study, we used actigraphy, the Pittsburgh Sleep Quality Index (PSQI), and Epworth Sleep Scale (ESS) to determine the clinical characteristics of sleep disorders in 116 patients with IE who were in rehabilitation after surgery.

Results

Our results showed that 46 (39.7%) patients had sleep efficiency over 85%, while 70 (60.3%) patients had sleep efficiency below 85%. The correlation analysis showed that sleep efficiency was related to the duration of the disease, with a longer duration leading to lower sleep efficiency (P=0.031). The sleep efficiency of patients with IE following surgery was also affected by alcohol consumption; however, surprisingly, patients with “heavy” alcohol consumption had higher sleep efficiency (P=0.030). We found a significant correlation between sleep efficiency and postoperative interleukin-6 (IL) levels, C-reactive protein (CRP) levels, and preoperative erythrocyte sedimentation rate (P<0.05). No significant correlation was found between brain natriuretic peptide levels and sleep efficiency, PSQI score, or ESS score. Postoperative hemoglobin (Hb) level was associated with sleep efficiency (R=0.194, P=0.036), but there was no statistically significant correlation between the PSQI and ESS scores. Postoperative alanine transaminase (ALT) showed a significant negative correlation with sleep efficiency (R=−0.27, P=0.003).

Conclusions

We found a high prevalence of sleep disorders in patients with IE along with an increase in inflammatory factors, including postoperative IL-6, CRP, ALT, and Hb levels.

Review of Wearable Devices and Data Collection Considerations for Connected Health

Wearable sensor technology has gradually extended its usability into a wide range of well-known applications. Wearable sensors can typically assess and quantify the wearer’s physiology and are commonly employed for human activity detection and quantified self-assessment. Wearable sensors are increasingly utilised to monitor patient health, rapidly assist with disease diagnosis, and help predict and often improve patient outcomes. Clinicians use various self-report questionnaires and well-known tests to report patient symptoms and assess their functional ability. These assessments are time consuming and costly and depend on subjective patient recall. Moreover, measurements may not accurately demonstrate the patient’s functional ability whilst at home. Wearable sensors can be used to detect and quantify specific movements in different applications. The volume of data collected by wearable sensors during long-term assessment of ambulatory movement can become immense in tuple size. This paper discusses current techniques used to track and record various human body movements, as well as techniques used to measure activity and sleep from long-term data collected by wearable technology devices.

Associations between health-related family environment and objective child sleep quality

AIM

This study aimed to assess the relationship between the family environment and behaviours with objective child sleep quality.

METHODS

Twenty-four children (aged 2-5 years) and their parents participated. Child sleep was assessed by accelerometer. Health of the family environment was quantified using the Family Nutrition and Physical Activity Screening Tool (FNPA). Exact Wilcoxon rank sum tests and linear regression were used to determine associations between FNPA scores and child sleep.

RESULTS

Healthier Total FNPA, Physical Activity FNPA, and Sleep Routine scores were associated with earlier bedtime. Healthier Sleep Routine score was associated with more total minutes of sleep per night. Healthier screen time-related FNPA construct scores were associated with earlier bedtime.

CONCLUSIONS

A composite score of family environment and behaviours, including physical activity- and nutrition-related constructs, was related to child sleep quality. Focus should be placed on the obesogenic family environment and healthy sleep routines to promote overall health among pre-school-aged populations.

Does investing in low-income urban neighborhoods improve sleep?

STUDY OBJECTIVES

Neighborhood disadvantage is associated with poor sleep, which may contribute to and exacerbate racial and socioeconomic health disparities. Most prior work has been cross-sectional and thus it has not been possible to estimate causal effects.

METHODS

We leveraged a natural experiment opportunity in two low-income, predominantly African American Pittsburgh, PA neighborhoods, following a randomly selected cohort of households (n = 676) between 2013 and 2016. One of the neighborhoods received substantial public and private investments (housing, commercial) over the study period, while the other socio-demographically similar neighborhood received far fewer investments. Primary analyses used a difference-in-difference analysis based on neighborhood, to examine changes in actigraphy-assessed sleep duration, efficiency, and wakefulness after sleep onset (WASO), and self-reported sleep quality. Secondary analyses examined whether residents' proximity to investments, regardless of neighborhood, was associated with changes in sleep outcomes.

RESULTS

Resident sleep worsened over time in both neighborhoods with no significant differences among residents between the two neighborhoods. Secondary analyses, including covariate adjustment and propensity score weighting to improve comparability, indicated that regardless of neighborhood, those who lived in closer proximity to investments (<0.1 mile) were significantly less likely to experience decreases in sleep duration, efficiency, and quality, or increases in WASO, compared to those who lived farther away.

CONCLUSIONS

While we did not observe sleep differences among residents between neighborhoods, living closer to a neighborhood investment was associated with better sleep outcomes. Findings have relevance for public health and policy efforts focused on investing in historically disinvested neighborhoods.

Sleep, evening light exposure and perceived stress in healthy nulliparous women in the third trimester of pregnancy

Objective

Sleep disturbances are common in pregnancy, and the prevalence increases during the third trimester. The aim of the present study was to assess sleep patterns, sleep behavior and prevalence of insomnia in pregnant women in the third trimester, by comparing them to a group of non-pregnant women. Further, how perceived stress and evening light exposure were linked to sleep characteristics among the pregnant women were examined.

Methods

A total of 61 healthy nulliparous pregnant women in beginning of the third trimester (recruited from 2017 to 2019), and 69 non-pregnant women (recruited in 2018) were included. Sleep was monitored by actigraphy, sleep diaries and the Bergen Insomnia Scale. The stress scales used were the Relationship Satisfaction Scale, the Perceived Stress Scale and the Pre-Sleep Arousal Scale. Total white light exposure three hours prior to bedtime were also assessed.

Results

The prevalence of insomnia among the pregnant women was 38%, with a mean score on the Bergen Insomnia Scale of 11.2 (SD = 7.5). The corresponding figures in the comparing group was 51% and 12.3 (SD = 7.7). The pregnant women reported lower sleep efficiency (mean difference 3.8; 95% CI = 0.3, 7.3), longer total sleep time derived from actigraphy (mean difference 59.0 minutes; 95% CI = 23.8, 94.2) and higher exposure to evening light (mean difference 0.7; 95% CI = 0.3, 1.2), compared to the non-pregnant group. The evening light exposure was inversely associated with total sleep time derived from actigraphy (B = -8.1; 95% CI = -14.7, -1.5), and an earlier midpoint of sleep (B = -10.3, 95% CI = -14.7, -5.9). Perceived stressors were unrelated to self-reported and actigraphy assessed sleep.

Conclusion

In healthy pregnant participants sleep in the third trimester was preserved quite well. Even so, the data suggest that evening light exposure was related to shorter sleep duration among pregnant women.

Sleep duration and physical performance during a 6-week military training course

Sleep is vital in influencing effective training adaptations in the military. This study aimed to assess the relationship between sleep and changes in physical performance over 6 weeks of military training. A total of 22 officer-trainees (age: 24 ± 5 years) from the New Zealand Defence Force were used for this prospective cohort study. Participants wore wrist-actigraphs to monitor sleep, completed subjective wellbeing questionnaires weekly, and were tested for: 2.4-km run time-trial, maximum press-up and curl-ups before and after 6 weeks of training. Average sleep duration was calculated over 36 nights (6:10 ± 0:28 hr:min), and sleep duration at the mid-point (6:15 hr:min) was used to stratify the trainees into two quantile groups (UNDERS: 5:51 ± 0:29 hr:min, n = 11) and (OVERS: 6:27 ± 0:09 hr:min, n = 11). There were no significant group × time interactions for 2.4-km run, press-ups or curl-ups (p > .05); however, small effects were observed in favour of OVERS for 2.4-km run (59.8 versus 44.9 s; d = 0.26) and press-ups (4.7 versus 3.2 reps; d = 0.45). Subjective wellbeing scores resulted in a significant group × time interaction (p < .05), with large effect sizes in favour of the OVERS group for Fatigue in Week 1 (d = 0.90) and Week 3 (d = 0.87), and Soreness in Week 3 (d = 1.09) and Week 4 (d = 0.95). Sleeping more than 6:15 hr:min per night over 6 weeks was associated with small benefits to aspects of physical performance, and moderate to large benefits on subjective wellbeing measures when compared with sleeping < 6:15 hr:min.

Validation Framework for Sleep Stage Scoring in Wearable Sleep Trackers and Monitors with Polysomnography Ground Truth

The rapid growth of point-of-care polysomnographic alternatives has necessitated standardized evaluation and validation frameworks. The current average across participant validation methods may overestimate the agreement between wearable sleep tracker devices and polysomnography (PSG) systems because of the high base rate of sleep during the night and the interindividual difference across the sampling population. This study proposes an evaluation framework to assess the aggregating differences of the sleep architecture features and the chronologically epoch-by-epoch mismatch of the wearable sleep tracker devices and the PSG ground truth. An AASM-based sleep stage categorizing method was proposed to standardize the sleep stages scored by different types of wearable trackers. Sleep features and sleep stage architecture were extracted from the PSG and the wearable device's hypnograms. Therefrom, a localized quantifier index was developed to characterize the local mismatch of sleep scoring. We evaluated different commonly used wearable sleep tracking devices with the data collected from 22 different subjects over 30 nights of 8-h sleeping. The proposed localization quantifiers can characterize the chronologically localized mismatches over the sleeping time. The outperformance of the proposed method over existing evaluation methods was reported. The proposed evaluation method can be utilized for the improvement of the sensor design and scoring algorithm.

A meta-analysis of accelerometer sleep outcomes in healthy children based on the Sadeh algorithm: the influence of child and device characteristics

STUDY OBJECTIVES

Children often experience sleep problems, with a negative impact on mood, behavior, cognitive function, and other aspects of mental and physical health. Accelerometers are widely used to assess sleep, but general reference values for healthy children do not yet exist. The aim of this meta-analysis was to determine mean values for wake after sleep onset (WASO), sleep efficiency (SE), total sleep time (TST) and sleep onset latency (SOL), and to determine the effect of child and accelerometer-characteristics.

METHODS

A search included studies with healthy children, 0-18 years, reporting WASO, SE, TST, and/or SOL, calculated with the Sadeh algorithm. Meta-analyses with random effects produced pooled estimate means per outcome. Meta-regression analyses determined the effect of age, sex, placement site and accelerometer type.

RESULTS

Eighty-three studies (9,068 participants) were included. Pooled means were 63 min (95% CI 57 to 69) for WASO, 88% (95% CI 87 to 89) for SE, 477 min (95% CI 464 to 491) for TST and 19 min (95% CI 17 to 22) for SOL. Heterogeneity was high (95%-99%). TST decreased with age and there was an age-effect on SOL. SE differed between wrist and ankle (used in age 0-24 months) placement, and between piezoelectric and MEMS-type accelerometers. No differences were found between boys and girls, although this number of studies was small.

CONCLUSIONS

We found differences in almost all investigated outcomes and heterogeneity was high. Therefore, we advise to use a study-specific control sample until more robust reference values are available. Future research should narrow the methodological heterogeneity and produce larger datasets, needed to establish these reference values.

Sleep in the Hospitalized Child: A Contemporary Review

Acute illness and hospitalization introduce several risk factors for sleep disruption in children that can negatively affect recovery and healing and potentially compromise long-term cognition and executive function. The hospital setting is not optimized for pediatric sleep promotion, and many of the pharmacologic interventions intended to promote sleep in the hospital actually may have deleterious effects on sleep quality and quantity. To date, evidence to support pharmacologic sleep promotion in the pediatric inpatient setting is sparse. Therefore, nonpharmacologic interventions to optimize sleep-wake patterns are of highest yield in a vulnerable population of patients undergoing active neurocognitive development. In this review, we briefly examine what is known about healthy sleep in children and describe risk factors for sleep disturbances, available sleep measurement tools, and potential interventions for sleep promotion in the pediatric inpatient setting.

Bi-directional relations between stress and self-reported and actigraphy-assessed sleep: a daily intensive longitudinal study

STUDY OBJECTIVES

Stress is associated with poor and short sleep, but the temporal order of these variables remains unclear. This study examined the temporal and bi-directional associations between stress and sleep and explored the moderating role of baseline sleep complaints, using daily, intensive longitudinal designs.

METHODS

Participants were 326 young adults (Mage = 23.24 ± 5.46), providing >2,500 nights of sleep altogether. Prospective total sleep time (TST), sleep onset latency (SOL), wake after sleep onset (WASO), and sleep efficiency (SE) were measured using actigraphy and sleep diaries. Perceived stress was reported three times daily between: 11:00-15:00, 15:30-19:30, and 20:00-02:00. Sleep complaints were measured at baseline using the PROMIS sleep disturbance scale. Within- and between-person sleep and stress variables were tested using cross-lagged multilevel models.

RESULTS

Controlling for covariates and lagged outcomes, within-person effects showed that higher evening stress predicted shorter actigraphic and self-reported TST (both p < .01). Conversely, shorter actigraphic and self-reported TST predicted higher next-day stress (both p < .001). Longer self-reported SOL and WASO (both p < .001), as well as lower actigraphic (p < .01) and self-reported SE (p < .001), predicted higher next-day stress. Between-person effects emerged only for self-reported TST predicting stress (p < .01). No significant results were found for the moderating role of baseline sleep complaints.

CONCLUSIONS

Results demonstrated bi-directional relations between stress and sleep quantity, and a consistent direction of worse sleep quantity and continuity predicting higher next-day stress. Results highlighted within-individual daily variation as being more important than between-individual differences when examining sleep and daytime functioning associations.

Changes in accelerometer-measured sleep during the transition to retirement: the Finnish Retirement and Aging (FIREA) study

STUDY OBJECTIVES

Retirement is associated with increases in self-reported sleep duration and reductions in sleep difficulties, but these findings need to be confirmed by using more objective measurement tools. This study aimed at examining accelerometer-based sleep before and after retirement and at identifying trajectories of sleep duration around retirement.

METHODS

The study population consisted of 420 participants of the Finnish Retirement and Aging study. Participants' sleep timing, sleep duration, time in bed, and sleep efficiency were measured annually using a wrist-worn triaxial ActiGraph accelerometer on average 3.4 times around retirement. In the analyses, sleep on nights before working days and on nights before days off prior to retirement were separately examined in relation to nights after retirement.

RESULTS

Both in bed and out bed times were delayed after retirement compared with nights before working days. Sleep duration increased on average by 41 min (95% confidence interval [CI] = 35 to 46 min) from nights before working days and decreased by 13 min (95% CI = -20 to -6 min) from nights before days off compared with nights after retirement. By using latent trajectory analysis, three trajectories of sleep duration around retirement were identified: (1) shorter mid-range sleep duration with increase at retirement, (2) longer mid-range sleep duration with increase at retirement, and (3) constantly short sleep duration.

CONCLUSIONS

Accelerometer measurements support previous findings of increased sleep duration after retirement. After retirement, especially out bed times are delayed, thus, closely resembling sleep on pre-retirement nights before non-working days.

Evidence That Sleep Is an Indicator of Overtraining during the Competition Phase of Adolescent Sprinters

Although sleep disturbance is a common complaint in overtrained athletes, the role of sleep in the overtraining process is not clear. This study aimed (i) to compare sleep efficiency/quantity at the start of a competition phase in elite adolescent sprinters who adapted to prior training with that in those who maladapt and (ii) to examine the influence of prior training, fatigue, and sleep on performance through a moderated mediation model. Fatigue (via Profile of Mood State) and internal training load (via session rating of perceived exertion and duration of training as volume) were measured in 20 sprinters (mean age: 15.9 ± 1.7 years) across 4 mesocycles (baseline (T1); preparatory (T2); precompetitive (T3); and competitive (T4) phases), over 26 weeks. Performances were assessed during the competitive period (T3, T4), while sleep was monitored (via actigraphy) for a week during T4. It was inferred that sprinters who had increasingly greater fatigue and concomitant decrements in performance (35%) were maladapted to training and the remaining sprinters who improved fatigue and performance (65%) were adapted to training. Sleep efficiency (91 ± 3% vs. 82 ± 3%, p < 0.001) and quantity (425 ± 33 min vs. 394 ± 20 min, p < 0.001) at the start of T4 were significantly greater in sprinters who adapted. Moreover, higher prior training volume (mean of T1 to T3 training volume) was associated with lower sleep efficiency at the start of T4 (R² = 0.55, p < 0.001) which was associated with poorer performance (R² = 0.82, p < 0.001). Fatigue moderated the indirect effect of prior training volume on performance through its moderation of the effect of sleep efficiency on performance (R² = 0.89, p < 0.001). Impaired sleep as a result of greater prior training volume may be related to performance decrements through fatigue. Athletes should improve sleep during periods of higher training volume to reduce fatigue for better adaptation to training.

A single-case multiple baseline design for treating insomnia in eating disorders: The TIRED study

OBJECTIVE

The purpose of this trial is to evaluate the novel use of an empirically supported treatment for sleep problems for people with residual insomnia disorder following ED treatment.

METHOD

Participants (N = 6) will complete a single-case multiple baseline study using Brief Behavioral Treatment for Insomnia (Buysse et al., Archives of Internal Medicine, 171, 2011, 887-895; Troxel et al., Behavioral Sleep Medicine, 10, 2012, 266-279). Participants will complete pre- and post-treatment evaluations of insomnia severity, sleep efficiency, daytime fatigue, ED symptoms, depressive symptoms, and anxiety symptoms. Throughout treatment, participants will complete daily diaries of sleep indices (sleep latency, wake after sleep onset, total sleep time, and sleep efficiency).

RESULTS

The primary outcome will be treatment effects on insomnia severity, measured by the Insomnia Severity Index. Secondary outcomes include sleep efficiency and daytime fatigue. Exploratory outcomes include ED-related impairment and symptoms, anxiety symptoms, and depression symptoms. We will provide subject-level graphs of sleep indices and ED symptoms throughout treatment. Additionally, treatment effects will be examined at one- and three-month follow-up.

DISCUSSION

Although insomnia treatments have been evaluated in other psychiatric disorders, there has yet to be a study examining behavioral interventions for insomnia in EDs. Results of this study will inform the development and application of interventions for residual insomnia symptoms in this population.

Sleep and functional capacity in adults: Cross-sectional associations among self-report and objective assessments

OBJECTIVES

This study examined the relationship between self-reported and objectively measured sleep and functional capacity in adults.

DESIGN

Cross-sectional.

PARTICIPANTS

Data were from the Midlife in the United States study. The sample consisted of men and women (n = 664) aged 25-83 who completed telephone interviews, questionnaires, and an overnight clinic stay.

MEASUREMENTS

Sleep was assessed by self-report (Pittsburgh Sleep Quality Index [PSQI]) and by objective measures (sleep latency, duration, wake after sleep onset [WASO], and midpoint/midpoint variability) from 7 consecutive days of actigraphy. Functional capacity was assessed by self-report of limitations and measured gait speed, grip strength, and chair stands.

RESULTS

In linear regression models adjusting for demographic and health factors, better self-reported sleep quality predicted fewer reported limitations, stronger grip, quicker gait, and faster chair stands (all P< .01). Greater WASO predicted more self-report limitations and slower gait speed (P< .05). Long (>8 hours) sleep duration and a more variable sleep schedule predicted lower grip strength (p < .05). Finally, after adjustment for objective sleep measures, PSQI remained a significant predictor of functional measures (P< .05) and explained a significant amount of additional variance (change in R²: 0.01-0.05).

CONCLUSIONS

The present results suggest that subjective and objective sleep measures capture distinct aspects of sleep that are independently related to functional capacity. The variance in functional measures explained by sleep variables, though small, was comparable to other risk factors for functional impairment (eg, obesity), underscoring the importance of associations between sleep and optimal function in adults.

The influence of intensity and timing of daily light exposure on subjective and objective sleep in adolescents with an evening circadian preference

STUDY OBJECTIVES

The aim of the present study is to examine the relationship between light and sleep, in adolescents with an evening circadian preference.

METHODS

For a period of seven days, ninety-nine adolescents wore a wrist actigraph to assess light exposure and objective sleep and completed a sleep diary to assess subjective sleep.

RESULTS

Lower average light intensity across the preceding 24 h was associated with a later sleep onset (p < 0.01) and a later next-day sleep offset (p < 0.05). A later time of last exposure to more than 10 lux was associated with a later sleep onset (p < 0.001) and a shorter objective total sleep time (p < 0.001), as well as a later bedtime (p < 0.001) and a shorter subjective total sleep time (p < 0.001). Furthermore, exploratory analyses found that lower average early morning light exposure (between 4 and 9 AM) was associated with later sleep onset (p < 0.05), a later next-day sleep offset (p < 0.05), and a later next-day waketime (p < 0.01), lower average afternoon light exposure (between 2 and 7 PM) was associated with a later next-day sleep offset (p < 0.05), and lower average evening light exposure (between 7 PM and 12 AM) was associated with longer subjective total sleep time (p < 0.01).

CONCLUSION

This study highlights the importance of light exposure, particularly the timing of light exposure, for establishing healthy patterns of sleep among adolescents with a propensity for a delayed bedtime and waketime. These findings provide additional evidence for targeting light exposure when designing interventions to improve adolescent sleep.

A Systematic Review of Sensing Technologies for Wearable Sleep Staging

Designing wearable systems for sleep detection and staging is extremely challenging due to the numerous constraints associated with sensing, usability, accuracy, and regulatory requirements. Several researchers have explored the use of signals from a subset of sensors that are used in polysomnography (PSG), whereas others have demonstrated the feasibility of using alternative sensing modalities. In this paper, a systematic review of the different sensing modalities that have been used for wearable sleep staging is presented. Based on a review of 90 papers, 13 different sensing modalities are identified. Each sensing modality is explored to identify signals that can be obtained from it, the sleep stages that can be reliably identified, the classification accuracy of systems and methods using the sensing modality, as well as the usability constraints of the sensor in a wearable system. It concludes that the two most common sensing modalities in use are those based on electroencephalography (EEG) and photoplethysmography (PPG). EEG-based systems are the most accurate, with EEG being the only sensing modality capable of identifying all the stages of sleep. PPG-based systems are much simpler to use and better suited for wearable monitoring but are unable to identify all the sleep stages.

Bidirectional Associations between Physical Activity and Sleep in Early-Elementary-Age Latino Children with Obesity

Low-income Latino children are at high risk for obesity and associated comorbidities. Considering the health benefits of proper sleep habits and physical activity, understanding the patterns, or the relationship between these modifiable factors may help guide intervention strategies to improve overall health in this population. Thus, the purpose was to investigate bidirectional associations between physical activity and sleep among Latino children who are overweight/obese. Twenty-three children (boys, 70%; overweight, 17%; obese, 83%) (age 7.9 ± 1.4 years) wore activity monitors on their wrist for 6 consecutive days (comprising 138 total observations). Hierarchical linear modeling evaluated temporal associations between physical activity (light physical activity, LPA; moderate to vigorous activity, MVPA) and sleep (duration and efficiency). Although there was no association between MVPA and sleep (p > 0.05), daytime LPA was negatively associated with sleep duration that night (estimate ± SE = -10.77 ± 5.26; p = 0.04), and nighttime sleep efficiency was positively associated with LPA the next day (estimate ± SE = 13.29 ± 6.16; p = 0.03). In conclusion, increased LPA may decrease sleep duration that night, but increasing sleep efficiency may increase LPA the following day. Although further investigation is required, these results suggest that improving sleep efficiency may increase the level of physical activity reached among Latino children who are overweight/obese.

Replacing school and out-of-school sedentary behaviors with physical activity and its associations with adiposity in children and adolescents: a compositional isotemporal substitution analysis

BACKGROUND

Little is known on how context-specific sedentary behaviors (SB) affect adiposity. This study aimed to investigate compositional associations between context-specific SB and adiposity and estimate the differences in adiposity associated with replacing school and out-of-school SB with physical activity (PA).

METHODS

This study included 336 children and adolescents. Time spent in SB and PA was estimated using multi-day 24-hour raw accelerometer data. SB and PA were specified for school and out-of-school times. Fat mass percentage (FM%) and fat mass index (FMI) were used as adiposity indicators. A compositional isotemporal substitution model was used to estimate differences in adiposity associated with one-to-one reallocations of time from context-specific SB to PA.

RESULTS

Participants spent approximately two thirds of their school and out-of-school time being sedentary. Relative to the remaining 24-h movement behaviors, significant associations between out-of-school SB and adiposity were found in both boys (β_ilr1 = 0.63, 95% confidence interval [CI] = 0.03-1.22 for FM%; β_ilr1 = 0.76, 95% CI = 0.03-1.49 for FMI) and girls (β_ilr1 = 0.62, 95% CI = 0.25-0.98 for FM%; β_ilr1 = 0.80, 95% CI = 0.28-1.32 for FMI). Replacing 30 min/day of out-of-school SB with out-of-school light PA decreased FM% by 10.1% (95% CI = 3.3-17.9) and FMI by 14% (95% CI = 2.7-24) in girls. No significant associations were found for school SB.

CONCLUSIONS

A reduction of out-of-school SB in favor of light PA should be advocated as an appropriate target for interventions and strategies to prevent childhood obesity.

An objective description of routine sleep habits in elite youth football players from the Middle-East

BACKGROUND AND STUDY OBJECTIVES

Adequate sleep is essential to support preparation and recovery processes for training and competition in athletes. A limited number of studies have examined whether adolescents from the Middle-East meet the minimum age-specific recommendations ranging from 8 to 9 h of night sleep based on objective measurements. This study aimed to provide an objective description of routine sleep habits in elite youth football players from the Middle-East.

METHODS

Using wrist-worn actigraphy, we examined objective measures of sleep over a 14-day surveillance period from fifty-nine, male, Middle-Eastern elite youth football players (age range: 12.1 to 16 years).

RESULTS

The observed median sleep duration was approximately 5.5 to 6 h during weekdays and 6.5 to 7.5 h over weekend days. Sleep intermissions resulting in two or more periods of sleep accounted for 8% and 17% of the data during weekdays and weekends, respectively.

CONCLUSIONS

For the first time, we reported an objective quantification of sleep measures indicating that elite youth athletes from the Middle-East do not meet the age-specific sleep recommendations. Integration of sleep tracking into the routine training monitoring process can be valuable to inform decisions relevant to the adoption of potential multidisciplinary interventions to address sleep insufficiency and disorders in youth athletes.

Multi-Night Validation of a Sleep Tracking Ring in Adolescents Compared with a Research Actigraph and Polysomnography

BACKGROUND

Wearable devices have tremendous potential for large-scale longitudinal measurement of sleep, but their accuracy needs to be validated. We compared the performance of the multisensor Oura ring (Oura Health Oy, Oulu, Finland) to polysomnography (PSG) and a research actigraph in healthy adolescents.

METHODS

Fifty-three adolescents (28 females; aged 15-19 years) underwent overnight PSG monitoring while wearing both an Oura ring and Actiwatch 2 (Philips Respironics, USA). Measurements were made over multiple nights and across three levels of sleep opportunity (5 nights with either 6.5 or 8h, and 3 nights with 9h). Actiwatch data at two sensitivity settings were analyzed. Discrepancies in estimated sleep measures as well as sleep-wake, and sleep stage agreements were evaluated using Bland-Altman plots and epoch-by-epoch (EBE) analyses.

RESULTS

Compared with PSG, Oura consistently underestimated TST by an average of 32.8 to 47.3 minutes (Ps < 0.001) across the different TIB conditions; Actiwatch 2 at its default setting underestimated TST by 25.8 to 33.9 minutes. Oura significantly overestimated WASO by an average of 30.7 to 46.3 minutes. It was comparable to Actiwatch 2 at default sensitivity in the 6.5, and 8h TIB conditions. Relative to PSG, Oura significantly underestimated REM sleep (12.8 to 19.5 minutes) and light sleep (51.1 to 81.2 minutes) but overestimated N3 by 31.5 to 46.8 minutes (Ps < 0.01). EBE analyses demonstrated excellent sleep-wake accuracies, specificities, and sensitivities - between 0.88 and 0.89 across all TIBs.

CONCLUSION

The Oura ring yielded comparable sleep measurement to research grade actigraphy at the latter's default settings. Sleep staging needs improvement. However, the device appears adequate for characterizing the effect of sleep duration manipulation on adolescent sleep macro-architecture.

Sleep assessment by means of a wrist actigraphy-based algorithm: agreement with polysomnography in an ambulatory study on older adults

The purpose of the present work is to examine, on a clinically diverse population of older adults (N = 46) sleeping at home, the performance of two actigraphy-based sleep tracking algorithms (i.e., Actigraphy-based Sleep algorithm, ACT-S1 and Sadeh's algorithm) compared to manually scored electroencephalography-based PSG (PSG-EEG). ACT-S1 allows for a fully automatic identification of sleep period time (SPT) and within the identified sleep period, the sleep-wake classification. SPT detected by ACT-S1 did not differ statistically from using PSG-EEG (bias = -9.98 min; correlation 0.89). In sleep-wake classification on 30-s epochs within the identified sleep period, the new ACT-S1 presented similar or slightly higher accuracy (83-87%), precision (86-89%) and F1 score (90-92%), significantly higher specificity (39-40%), and significantly lower, but still high, sensitivity (96-97%) compared to Sadeh's algorithm, which achieved 99% sensitivity as the only measure better than ACT-S1's. Total sleep times (TST) estimated with ACT-S1 and Sadeh's algorithm were higher, but still highly correlated to PSG-EEG's TST. Sleep quality metrics of sleep period efficiency and wake-after-sleep-onset computed by ACT-S1 were not significantly different from PSG-EEG, while the same sleep quality metrics derived by Sadeh's algorithm differed significantly from PSG-EEG. Agreement between ACT-S1 and PSG-EEG reached was highest when analyzing the subset of subjects with least disrupted sleep (N = 28). These results provide evidence of promising performance of a full-automation of the sleep tracking procedure with ACT-S1 on older adults. Future longitudinal validations across specific medical conditions are needed. The algorithm's performance may further improve with integrating multi-sensor information.

Ethnicity Differences in Sleep Changes Among Prehypertensive Adults Using a Smartphone Meditation App: Dose-Response Trial

Background

African Americans (AAs) experience greater sleep quality problems than non-Hispanic Whites (NHWs). Meditation may aid in addressing this disparity, although the dosage levels needed to achieve such benefits have not been adequately studied. Smartphone apps present a novel modality for delivering, monitoring, and measuring adherence to meditation protocols.

Objective

This 6-month dose-response feasibility trial investigated the effects of a breathing awareness meditation (BAM) app, Tension Tamer, on the secondary outcomes of self-reported and actigraphy measures of sleep quality and the modulating effects of ethnicity of AAs and NHWs.

Methods

A total of 64 prehypertensive adults (systolic blood pressure <139 mm Hg; 31 AAs and 33 NHWs) were randomized into 3 different Tension Tamer dosage conditions (5,10, or 15 min twice daily). Sleep quality was assessed at baseline and at 1, 3, and 6 months using the Pittsburgh Sleep Quality Index (PSQI) and 1-week bouts of continuous wrist actigraphy monitoring. The study was conducted between August 2014 and October 2016 (IRB #Pro00020894).

Results

At baseline, PSQI and actigraphy data indicated that AAs had shorter sleep duration, greater sleep disturbance, poorer efficiency, and worse quality of sleep (range P=.03 to P<.001). Longitudinal generalized linear mixed modeling revealed a dose effect modulated by ethnicity (P=.01). Multimethod assessment showed a consistent pattern of NHWs exhibiting the most favorable responses to the 5-min dose; they reported greater improvements in sleep efficiency and quality as well as the PSQI global value than with the 10-min and 15-min doses (range P=.04 to P<.001). Actigraphy findings revealed a consistent, but not statistically significant, pattern in the 5-min group, showing lower fragmentation, longer sleep duration, and higher efficiency than the other 2 dosage conditions. Among AAs, actigraphy indicated lower sleep fragmentation with the 5-min dose compared with the 10-min and 15-min doses (P=.03 and P<.001, respectively). The 10-min dose showed longer sleep duration than the 5-min and 15-min doses (P=.02 and P<.001, respectively). The 5-min dose also exhibited significantly longer average sleep than the 15-min dose (P=.03).

Conclusions

These findings indicate the need for further study of the potential modulating influence of ethnicity on the impact of BAM on sleep indices and user-centered exploration to ascertain the potential merits of refining the Tension Tamer app with attention to cultural tailoring among AAs and NHWs with pre-existing sleep complaints.

Impact of a Sleep Enhancement Protocol on Nighttime Room Entries in an Inpatient Rehabilitation Facility

PURPOSE

This study examined whether a sleep enhancement protocol (SEP) could reduce nighttime room entries (NREs) for patients with orthopedic injury (OI) or acquired brain injury (ABI) in an inpatient rehabilitation facility.

DESIGN

A two-wave prospective study assessing standard of care (SOC) versus SEP.

METHODS

Sixty-five participants completed baseline and follow-up questionnaires and wore an actigraph for approximately 7 days. In the SEP, nighttime care was "bundled."

FINDINGS

In SOC, NREs were associated with less efficient sleep and greater daytime fatigue. Nighttime room entries were approximately 50% lower in the SEP than SOC. Participants in the OI SOC had more room entries than any other group. There were no significant changes in room entries in the ABI SEP group.

CONCLUSIONS

There was a relationship between NREs and sleep. The SEP was effective at reducing NREs for patients with OI, but not ABI.

CLINICAL RELEVANCE

Sleep enhancement protocols in inpatient rehabilitation facilities may be effective at improving sleep. Future research may focus on developing individualized protocols to improve sleep across patients with a variety of presenting diagnoses.

Short-term efficacy of home-based heart rate variability biofeedback on sleep disturbance in patients with incurable cancer: a randomised open-label study

OBJECTIVES

Early palliative care reportedly contributes to the quality of life by improving coping skills in patients with cancer. The aims of the study are to (1) Build a self-coping system that makes it possible to perform a session of home-based heart rate variability biofeedback (HRV-BF) with resonant breathing in patients with sleep disturbance and to acquire its techniques early on, and (2) Examine its short-term efficacy and feasibility.

METHODS

A randomised, open-label, comparative study was conducted in the presence or absence of home-based HRV-BF with resonant breathing using a portable HRV-BF device prior to bedtime. The participants were 50 patients with incurable cancer with sleep disturbance who underwent a hospital practice of HRV-BF with resonant breathing. The primary end point was the rate of change in sleep efficiency for 10-14 days. The Japanese version of the Pittsburgh Sleep Quality Index (subjective indicator) and actigraphy sleep parameters (objective indicators) were used for sleep assessments.

RESULTS

The completion rate and implementation rate in the home-based HRV-BF group (n=25) were 96.0% and 91.4%, respectively. This group showed a significant improvement in sleep efficiency, sleep duration and the low-frequency component of HRV. Sleep latency worsened in this group, but a significant difference was not observed.

CONCLUSIONS

A home practice of HRV-BF with resonant breathing made it possible to acquire its techniques early on and improve sleep and autonomic function; therefore, our study showed high short-term efficacy and feasibility required for a self-coping system.

Association of sleep with cognition and beta amyloid accumulation in adults with Down syndrome

Adults with Down syndrome have an increased risk for both disordered sleep and Alzheimer's disease (AD). In the general population, disrupted sleep has been linked to beta amyloid accumulation, an early pathophysiologic feature of AD. In this study, the association among sleep, beta amyloid, and measures of AD-related cognitive decline was examined in 47 non-demented adults with Down syndrome (aged 26-56 years). Sleep was measured using actigraphy over 7 nights. Pittsburgh Compound B positron emission tomography was used to assess global and striatal beta amyloid burden. Participants had the following clinical AD status: 7 (15%) mild cognitive impairment and 40 (85%) cognitively unaffected. Average length of night-time awakenings was significantly positively associated with striatal beta amyloid and decreased cognitive performance in executive functioning and motor planning and coordination. Findings suggest that disrupted sleep is associated with beta amyloid accumulation and cognitive features of preclinical AD in Down syndrome. Early identification and treatment of sleep problems could be a lifestyle intervention that may delay beta amyloid accumulation and cognitive decline in this AD vulnerable group.

Quantifying postoperative sleep loss associated with increased pain in children undergoing a modified Nuss operation

PURPOSE

The presence of pain may interrupt sleep and impede normal postoperative recovery; however, no prior studies have quantified sleep loss due to pain in children undergoing inpatient surgery. Wearable accelerometers objectively measure sleep patterns in children. We aimed to quantify sleep loss associated with patient reported pain scores after a Modified Nuss operation.

METHODS

Ten patients undergoing Modified Nuss operations were recruited during their inpatient stay. Children wore an Actigraph GT3X-BT accelerometer postoperatively during their hospital stay. Hourly sleep minutes were recorded using the Actigraph between 10 pm and 6 am. Patient reported pain scores were abstracted from patient charts. Mixed linear regression models, adjusting for within-subject random effects, were estimated to quantify the association between hourly sleep minutes and patient reported pain scores.

RESULTS

Patients were 30% female, with an average age of 15.7 years (range 13-22). The majority (70%) of patients were white non-Hispanic. All patients received a patient controlled analgesic pump. Average postoperative length of stay was 4.8 days (range 4.0-6.0; SD = 0.8). A total of 240 sleep hours and associated pain scores were analyzed. Patients slept on average 48 min per hour. Mixed model analysis predicted that a 1-point increase in pain score was associated with 2.5 min per hour less sleep time.

CONCLUSION

Increases in patient-reported pain scores are associated with sleep loss after a Modified Nuss operation. Objectively quantifying sleep loss associated with postoperative pain using accelerometer data may help clinicians better understand their patient's level of pain control. Our findings provide the basis for future studies aimed at more accurately titrating pain medication to optimize sleep and speed up recovery.

LEVEL OF EVIDENCE

Case Series Without Comparison Group, Level IV.

Treating subclinical and clinical symptoms of insomnia with a mindfulness-based smartphone application: A pilot study

BACKGROUND/OBJECTIVES

Emerging research suggests that face-to-face group mindfulness-based therapies are an effective intervention for insomnia. This pilot study examined the effectiveness of a mindfulness-based smartphone application for improving objectively-measured sleep, self-reported sleep, insomnia severity, pre-sleep arousal and daytime mood.

METHOD

A community sample of 23 adults with subclinical to moderately severe symptoms of insomnia were randomized to either a mindfulness or progressive muscle relaxation (PMR) smartphone application for 40 or 60 days. Objective sleep outcomes assessed using actigraphy, and self-report measures of total wake time, cognitive and somatic pre-sleep arousal, and daytime positive and negative affect were assessed for 14 nights at baseline and post-intervention. Insomnia severity was recorded at baseline and post-intervention.

RESULTS

A greater reduction in sleep onset latency was observed in the mindfulness group over time, relative to the PMR group. The mindfulness group also reported medium effect size improvements for sleep efficiency. No significant interaction effects were found for self-reported sleep measures, however, main effects of time were found for both groups for total wake time, insomnia severity, cognitive pre-sleep arousal, and daytime positive and negative affect.

CONCLUSIONS

These preliminary findings suggest that both mindfulness and PMR smartphone applications have the potential to improve symptoms of insomnia. In particular, this mindfulness-based smartphone application may improve sleep onset latency and reduce the duration of night-awakenings. Further research exploring digital therapeutics as a self-help option for those with insomnia is needed.

The impact of narratives and active video games on long-term moderate-to-vigorous physical activity: A randomized controlled trial protocol

BACKGROUND

Although physical activity (PA) has been shown in helping prevent and treat obesity, current PA interventions are still not effective in ameliorating the obesity epidemic. Additional forms of PA need to be investigated to improve PA engagement and outcomes. We hypothesize that pairing a narrative (i.e., story) with an active video game (AVG), a less traditional form of PA, will increase participant engagement in PA. This paper presents the rationale, implementation, and pilot results of a study assessing the effect of narrative's impact on PA and a series of other health outcomes.

OBJECTIVE

This paper presents the rationale, implementation, and pilot results of a study assessing the effect of narrative's impact on PA and a series of other health outcomes.

METHODS/DESIGN

The Active Video Game Study is a six-month randomized controlled single-blind trial projected to include 210 participants. The intervention strategy will pair a narrative to an active video game (AVG). Participants will be randomized into 3 groups: condition A [Narrative + AVG], condition B [AVG Only], and condition C [Control]. Participants will undergo three in-person data collection visits over the course of six months. Inclusion criteria are that children are between the ages of 8-12 and have a BMI ≥ 85%. The primary outcome is change in moderate to vigorous physical activity (MVPA). Secondary outcome measures include change in BMI percentile, fasting insulin and glucose, lipid panel, C-reactive protein, and cognitive function. A pilot trial of n = 6 was conducted to help develop procedures and address problems that could arise in the main trial.

DISCUSSION

Successful completion of this study will provide the empirical basis for novel intervention and design strategies to enhance the impact of AVGs on long-term MVPA.

Impact of change in bedtime variability on body composition and inflammation: secondary findings from the Go Red for Women Strategically Focused Research Network

Variability in daily sleep patterns is an emerging factor linked to metabolic syndrome. However, whether reducing bedtime variability improves markers of disease risk has not been tested. Here, we assessed whether body composition and inflammation were impacted by changes in bedtime variability over a 6-week period, during which, women were instructed to maintain healthy, habitual sleep (HS) patterns (one arm of a randomized trial). Data were available for 37 women (age 34.9 ± 12.4 years, BMI 24.7 ± 2.9 kg/m2, sleep duration 7.58 ± 0.49 h/night). Body composition and leukocyte platelet aggregates (LPA) were measured at baseline and endpoint using magnetic resonance imaging and flow cytometry, respectively. Sleep data were collected daily using wrist actigraphy. Change in bedtime variability was calculated as the difference in the standard deviation (SD) of bedtimes measured during the 2-week screening period and the 6-week intervention period. Results showed that women who reduced their bedtime variability (n = 29) during the intervention had reductions in total (P < 0.001) and subcutaneous adipose tissue (P < 0.001) relative to women who increased/maintained (n = 8) bedtime variability. Similar effects were observed for LPA levels between women who reduced vs increased/maintained bedtime variability (P = 0.011). Thus, reducing bedtime variability, without changing sleep duration, could improve cardiometabolic health by reducing adiposity and inflammation.

Effects of acute sleep deprivation on H reflex and V wave

The impact of sleep deprivation on muscular strength and power remains poorly understood. We aimed to determine the acute effects of 24 hr of sleep deprivation on H-reflex and V-wave excitability. Fourteen healthy young adults (eight men, six women) were included. Participants visited the laboratory on two different occasions, without and with 24 hr of sleep deprivation. In each session, participants were tested for maximal voluntary contraction (MVC) of the plantar flexors and dorsiflexors, soleus H- and M-recruitment curves, and evoked V wave, as well as tibialis anterior/soleus electromyographic co-activation. Twenty-four hours of sleep deprivation did not affect either plantarflexion MVC or soleus electromyographic normalized amplitude (p > .05). Moreover, H-reflex and V-wave peak-to-peak normalized amplitude did not change with sleep deprivation (p > .05). Conversely, we obtained a significant increase in antagonist/agonist level of co-activation during MVC post-sleep deprivation (6.2 ± 5.2%, p < .01). In conclusion, we found that H-reflex and V-wave responses are well preserved after 24 hr of sleep deprivation, revealing that descending neural drive and/or modulation in Ia afferent input remains largely unaffected under these circumstances. Yet, sleep deprivation affects motor control by exacerbating the magnitude of antagonist/agonist co-activation during forceful muscle contractions and this is novel.

The Impact of Optimized Daylight and Views on the Sleep Duration and Cognitive Performance of Office Workers

A growing awareness has recently emerged on the health benefits of exposure to daylight and views. Daylight exposure is linked to circadian rhythm regulation, which can have significant impacts on sleep quality and cognitive function. Views of nature have also been shown to impact emotional affect and performance. This study explores the impact of optimized daylight and views on the sleep and cognitive performance of office workers. Thirty knowledge workers spent one week working in each of two office environments with identical layouts, furnishings, and orientations; however, one was outfitted with electrochromic glass and the other with traditional blinds, producing lighting conditions of 40.6 and 316 equivalent melanopic lux, respectively. Participants in the optimized daylight and views condition slept 37 min longer as measured by wrist-worn actigraphs and scored 42% higher on cognitive simulations designed to test their higher order decision-making performance. Both sleep and cognitive function were impacted after one day in the space, yet the impacts became more significant over the course of the week. The positive effect of optimized daylight and views on cognitive function was comparable for almost all participants, while increases in sleep duration were significantly greater for those with the lowest baseline sleep duration. This study stresses the significance of designing with daylight in order to optimize the sleep quality and performance of office workers.

Sleep Characteristics and Measures of Glucose Metabolism in Blacks: The Jackson Heart Study

Background Characterizing associations of sleep characteristics with blood-glucose-level factors among blacks may clarify the underlying mechanisms of impaired glucose metabolism and help identify treatment targets to prevent diabetes mellitus in blacks. Methods and Results Cross-sectional analyses were conducted in 789 blacks who completed home sleep apnea testing and 7-day wrist actigraphy in 2012-2016. Sleep-disordered breathing measurements included respiratory event index associated with 4% oxygen desaturation and minimum oxygen saturation. Sleep patterns on actigraphy included fragmented sleep indices. Associations between sleep characteristics (8 exposures) and measures of glucose metabolism (3 outcomes) were determined using multivariable linear regression. Mean (SD) age of the participants was 63 (11) years; 581 (74%) were women; 198 (25%) were diabetes mellitus, and 158 (20%) were taking antihyperglycemic medication. After multivariable adjustment, including antihyperglycemic medication use, the betas (95% CI) for fasting glucose and hemoglobin A1c, respectively, for each SD higher level were 0.13 (0.02, 0.24) mmol/L and 1.11 (0.42, 1.79) mmol/mol for respiratory event index associated with 4% oxygen desaturation and 0.16 (0.05, 0.27) mmol/L and 0.77 (0.10, 1.43) mmol/mol for fragmented sleep indices. Among 589 participants without diabetes mellitus, the betas (95% CI) for homeostatic model assessment of insulin resistance for each SD higher level were 1.09 (1.03, 1.16) for respiratory event index associated with 4% oxygen desaturation, 0.90 (0.85, 0.96) for minimum oxygen saturation, and 1.07 (1.01, 1.13) for fragmented sleep indices. Conclusions Sleep-disordered breathing, overnight hypoxemia, and sleep fragmentation were associated with higher blood glucose levels among blacks.

The impact of sleep loss on sustained and transient attention: an EEG study

Sleep is one of our most important physiological functions that maintains physical and mental health. Two studies examined whether discrete areas of attention are equally affected by sleep loss. This was achieved using a repeated-measures within-subjects design, with two contrasting conditions: normal sleep and partial sleep restriction of 5-h. Study 1 compared performance on a sustained attention task (Psychomotor Vigilance task; PVT) with performance on a transient attention task (Attentional Blink; AB). PVT performance, but not performance on the AB task, was impaired after sleep restriction. Study 2 sought to determine the neural underpinnings of the phenomenon, using electroencephalogram (EEG) frequency analysis, which measured activity during the brief eyes-closed resting state before the tasks. AB performance was unaffected by sleep restriction, despite clearly observable changes in brain activity. EEG results showed a significant reduction in resting state alpha oscillations that was most prominent centrally in the right hemisphere. Changes in individual alpha and delta power were also found to be related to changes in subjective sleepiness and PVT performance. Results likely reflect different levels of impairment in specific forms of attention following sleep loss.

Presleep α-Lactalbumin Consumption Does Not Improve Sleep Quality or Time-Trial Performance in Cyclists

We tested the hypothesis that presleep consumption of α-lactalbumin (LA), a fraction of whey with a high abundance of tryptophan, would improve indices of sleep quality and time-trial (TT) performance in cyclists relative to an isonitrogenous collagen peptide (CP) supplement lacking tryptophan. Using randomized, double-blind, crossover designs, cyclists consumed either 40 g of LA or CP 2 hr prior to sleep. In Study 1, six elite male endurance track cyclists (age 23 ± 6 years, V˙O2peak 70.2 ± 4.4 ml·kg-1·min-1) consumed a supplement for three consecutive evenings before each 4-km TT on a velodrome track, whereas in Study 2, six well-trained cyclists (one female; age 24 ± 5 years, V˙O2peak 66.9 ± 8.3 ml·kg-1·min-1) consumed a supplement the evening before each 4-km TT on a stationary cycle ergometer. Indices of sleep quality were assessed with wrist-based actigraphy. There were no differences between the CP and LA supplements in terms of total time in bed, total sleep time, or sleep efficiency in Study 1 (LA: 568 ± 71 min, 503 ± 67 min, 88.3% ± 3.4%; CP: 546 ± 30 min, 479 ± 35 min, 87.8% ± 3.1%; p = .41, p = .32, p = .74, respectively) or Study 2 (LA: 519 ± 90 min, 450 ± 78 min, 87.2% ± 7.6%; CP: 536 ± 62 min, 467 ± 57 min, 87.3% ± 6.4%; p = .43, p = .44, p = .97, respectively). Similarly, time to complete the 4-km TT was unaffected by supplementation in Study 1 (LA: 274.9 ± 7.6 s; CP: 275.5 ± 7.2 s; p = .62) and Study 2 (LA: 344.3 ± 22.3 s; CP: 343.3 ± 23.0 s; p = .50). Thus, relative to CP, consuming LA 2 hr prior to sleep over 1-3 days did not improve actigraphy-based indices of sleep quality or 4-km TT performance in cyclists.

Broken Windows, Broken Zzs: Poor Housing and Neighborhood Conditions Are Associated with Objective Measures of Sleep Health

African Americans and socioeconomically disadvantaged individuals have higher rates of a variety of sleep disturbances, including short sleep duration, poor sleep quality, and fragmented sleep. Such sleep disturbances may contribute to pervasive and widening racial and socioeconomic (SES) disparities in health. A growing body of literature demonstrates that over and above individual-level SES, indicators of neighborhood disadvantage are associated with poor sleep. However, there has been scant investigation of the association between sleep and the most proximal environments, the home and residential block. This is the first study to examine the association between objective and self-reported measures of housing and block conditions and sleep. The sample included 634 adults (mean age = 58.7 years; 95% African American) from two low-income urban neighborhoods. Study participants reported whether they experienced problems with any of seven different housing problems (e.g., broken windows) and rated the overall condition of their home. Trained data collectors rated residential block quality. Seven days of wrist actigraphy were used to measure average sleep duration, efficiency, and wakefulness after sleep onset (WASO), and a sleep diary assessed sleep quality. Multivariate regression analyses were conducted for each sleep outcome with housing or block conditions as predictors in separate models. Participants reporting "fair" or "poor" housing conditions had an adjusted average sleep duration that was 15.4 min shorter than that of participants reporting "good" or "excellent" conditions. Those reporting any home distress had 15.9 min shorter sleep and .19 units lower mean sleep quality as compared with participants who did not report home distress. Poor objectively measured block quality was associated with 14.0 min shorter sleep duration, 1.95% lower sleep efficiency, and 10.7 additional minutes of WASO. Adverse housing and proximal neighborhood conditions are independently associated with poor sleep health. Findings highlight the importance of considering strategies that target upstream determinants of sleep health disparities.

Objective Measures of Sleep Apnea and Actigraphy-Based Sleep Characteristics as Correlates of Subjective Sleep Quality in an Epidemiologic Study: The Jackson Heart Sleep Study

OBJECTIVE

Self-reported "sleep quality" often is assessed in epidemiologic studies. However, the bases for variation in sleep quality is not fully understood. We quantified the extent to which subjective sleep quality was related to sleep disorders and sleep characteristics among 795 African American adults.

METHOD

Between 2012 and 2016, participants underwent home sleep apnea testing and 1-week actigraphy (estimating sleep duration, efficiency, fragmentation, latency). Sleep quality, insomnia and restless legs syndrome symptoms, sleepiness, and physician diagnosis of sleep disorders were self-reported. We fit linear regression models to determine the extent to which subjective and objective sleep measures as well as depressive symptoms and anxiety were related to subjective sleep quality.

RESULTS

After adjustment for covariates, worse sleep quality scores were associated with insomnia and restless legs syndrome symptoms, sleep apnea, physician diagnosis of a sleep disorder, and actigraphy-based fragmented sleep, lower sleep efficiency, and shorter sleep duration. Insomnia symptoms explained the most variance in subjective sleep quality, 21%. Other sleep measures each explained 3% to 7% and psychosocial factors explained 8% to 9% of the variance in subjective sleep quality after adjustment for confounders.

CONCLUSIONS

The weak associations of sleep quality with sleep disorders and objectively measured sleep disturbances are consistent with concepts of "sleep health" as a multidimensional construct. Sleep quality is a patient-centered outcome that provides unique information over objective measurements of sleep disturbances.

Actigraphic estimates of sleep and the sleep-wake rhythm, and 6-sulfatoxymelatonin levels in healthy Dutch children

Sleep and the sleep-wake rhythm are essential for children's health and well-being, yet reference values are lacking. This study therefore aimed to assess actigraphic estimates of sleep and the 24-h sleep-wake rhythm, as well as 6-sulfatoxymelatonin (aMT6s) levels in healthy children of different age groups. Additionally, relationships between the outcomes and sex, highest parental educational level (as an indication of socioeconomic status (SES)), and body-mass-index (BMI) were explored. In this cross-sectional study, healthy Dutch children (2-18 years) wore an actigraph (GT3x) for 7 consecutive days, collected first-morning void urine and completed a sleep log and sociodemographic questionnaire. Actigraphically estimated sleep variables were sleep onset latency (SOL), sleep efficiency (SE), total sleep time (TST), and wake after sleep onset (WASO). Non-parametric sleep-wake rhythm variables were intradaily variability (IV); interdaily stability (IS); the activity counts and timing of the least active 5-h period (L5counts and midpoint) and of the most active 10-h period (M10 counts and midpoint); and the relative amplitude (RA), i.e. the ratio of the difference and the sum of M10 and L5 counts. Finally, creatinine-corrected aMT6s levels were obtained by isotope dilution mass spectrometry. Effects of age group (preschool 2-5 years/school-aged 6-12 years/teenager 13-18 years), sex, highest parental educational level and BMI (Z-scores) were explored. Ninety-four children participated, equally divided across age groups (53% boys). Teenagers slept less, but more efficiently, than younger children, while their 24 h sleep-wake rhythm was the least stable and most fragmented (likely due to fragmentation of daytime activity). Additionally, aMT6s levels significantly declined over the age groups. Children from highly educated parents had lower sleep efficiency, but a more stable sleep-wake rhythm. Finally, sex or increase in BMI was not associated with any of the outcomes in this study. In conclusion, this study provides reference values of healthy children across different age groups and different sociodemographic factors. In the future, this information may help to better interpret outcomes in clinical populations.

Assessing the effects of sleep on neurocognitive performance and injury rate in adolescent athletes using actigraphy

The National Sleep Foundation recommends that adolescents (age 14-17 years) sleep 8 to 10 hours per night. Sleep loss is associated with cognitive dysfunction, decreased reaction time, and poorer athletic performance. This study evaluated the effects of sleep on sports injury rate and academic and cognitive performance. Seventeen high school track and field athletes (7 males, 10 females, mean age 15.9 years) wore an actigraph device for 10 weeks and performed a computerized neurocognitive assessment. Overall, 900 nights of nocturnal sleep data were analysed. Total minutes in bed averaged 501 minutes (8 hours and 21 minutes) and total sleep time averaged 378 minutes (6 hours and 18 minutes). Statistically significant correlations were observed between mean total sleep time and age-adjusted scores for the neurocognitive domains of episodic memory (p = .03) and fluid cognition (p = .03). Sleep loss in student-athletes may result in greater cognitive difficulties and impair academic abilities in the classroom.