Seasonal and weather variation of sleep and physical activity in 12-14-year-old children.

Background: Understanding variation in physical activity (PA) and sleep is necessary to develop novel intervention strategies targeting adolescents' health behaviors. We examined the extent to which PA and sleep vary by aspects of the physical environment. Participants: We performed a cross-sectional analysis of 669 adolescents in the Project Viva cohort. Methods: We estimated total PA, sleep duration, sleep efficiency, and sleep midpoint timing from wrist accelerometers. We used multivariable linear regression models and generalized estimated equations to assess associations of PA and sleep with season and daily weather conditions obtained from the National Oceanic and Atmospheric Administration archive. Results: Mean age was 12.9 (SD 0.6) years; 51% were female and 68% were white. Mean sleep duration was 466 (SD 42) min per night and total PA was 1,652 (SD 431) counts per min per day. Sleep midpoint time was 41 (95% CI: 27 to 54) min later in summer, 28 (95% CI: -41 to -14) min earlier in spring, and 29 (95% CI: -43 to -15) min earlier in autumn compared to winter. Higher temperature and longer day length both were associated with small reductions of nightly sleep duration. Adolescents were less physically active during winter and on rainy and short sunlight days. There was an inverse U-shaped relationship between PA and mean temperature. Conclusions: Season was associated with large changes in sleep timing, and smaller changes in other sleep and PA measurements. Given the importance of sleep and circadian alignment, future health behavioral interventions may benefit by targeting "season-specific" interventions.

Longitudinal association of actigraphy-assessed sleep with physical growth in the first 6 months of life.

STUDY OBJECTIVES: Suboptimal sleep is associated with obesity and its sequelae in children and adults. However, few studies have examined the association between sleep and physical growth in infants who experience rapid changes in sleep/wake patterns. We examined the longitudinal association of changes in objectively assessed sleep/wake patterns with changes in growth between ages 1 and 6 months. METHODS: We studied 298 full-term infants in the longitudinal Rise & SHINE cohort study. Changes from 1 and 6 months in nighttime sleep duration, wake after sleep onset (WASO), and number of waking bouts ≥5 min were assessed using ankle actigraphy. Overweight was defined as age- and sex-specific weight for length ≥95th percentile. Generalized estimating equation analyses adjusted for infants' and mothers' characteristics. RESULTS: The mean (SD) birth weight was 3.4 (0.4) kg; 48.7% were boys. In multivariable adjusted models, each 1-h increase in nighttime sleep duration between months 1 and 6 was associated with a 26% decrease in the odds of overweight from 1 to 6 months (odds ratio [OR] = 0.74; 95% confidence interval [CI, 0.56, 0.98]). Each 1-unit decrease in number of waking bouts was associated with a 16% decrease in the odds of overweight (OR = 0.84; 95% CI [0.72, 0.98]). Changes in WASO were not associated with the odds of overweight. CONCLUSIONS: Greater increases in nighttime sleep duration and more consolidation of nighttime sleep were associated with lower odds of overweight from 1 to 6 months. Adverse sleep patterns as early as infancy may contribute to excess adiposity.

Associations of sleep-related behaviors and the sleep environment at infant age one month with sleep patterns in infants five months later.

OBJECTIVE: To characterize family and environmental correlates of sleep patterns that may contribute to differences in infant sleep. METHODS: We studied 313 infants in the Rise & SHINE (Sleep Health in Infancy & Early Childhood study) cohort. Our main exposures were the parent-reported sleep environment, feeding method and sleep parenting strategies at infant age one month. The main outcomes were nighttime sleep duration, longest nighttime sleep and number of awakenings measured by actigraphy at age six months. We used multivariable linear regression models to examine associations, and secondarily also explored the role of sleep-related environmental exposures in mediating previously observed associations of racial/ethnicity and parental education with infant sleep characteristics. RESULTS: In adjusted models, a non-dark sleep environment (versus an always dark sleep location) and taking the baby to parent's bed when awake at night (versus no co-sleeping) were associated with 28 (95% CI, -45, -11) and 18 (95% CI, -33, -4) minutes less sleep at night, respectively. Bottle feeding at bedtime was associated with 62 (95% CI, 21, 103) minutes additional longest nighttime sleep period. Exploratory mediation analyses suggested a modest mediating role of a non-dark sleep environment on racial/ethnic and educational differences in sleep duration. CONCLUSIONS: Infant sleep duration was positively associated with a dark sleep environment and a focal feed at bedtime while taking the baby to the parent's bed was associated with reduced infant sleep. Modifying the sleep environment and practices may improve infant sleep and reduce sleep health disparities.

Emergence of racial/ethnic and socioeconomic differences in objectively measured sleep-wake patterns in early infancy: results of the Rise & SHINE study.

STUDY OBJECTIVES: To characterize objectively assessed sleep-wake patterns in infants at approximately 1 month and 6 months and examine the differences among infants with different racial/ethnic backgrounds and household socioeconomic status (SES). METHODS: Full-term healthy singletons wore an ankle-placed actigraph at approximately 1 month and 6 months and parents completed sleep diaries. Associations of racial/ethnic and socioeconomic indices with sleep outcomes were examined using multivariable analyses. Covariates included sex, birth weight for gestational age z-score, age at assessment, maternal education, household income, bed-sharing, and breastfeeding. RESULTS: The sample included 306 infants, of whom 51% were female, 42.5% non-Hispanic white, 32.7% Hispanic, 17.3% Asian, and 7.5% black. Between 1 month and 6 months, night sleep duration increased by 65.7 minutes (95% CI: 55.4, 76.0), night awakenings decreased by 2.2 episodes (2.0, 2.4), and daytime sleep duration decreased by 73.3 minutes (66.4, 80.2). Compared to change in night sleep duration over this development period for white infants (82.3 minutes [66.5, 98.0]), night sleep increased less for Hispanic (48.9 minutes [30.8, 66.9]) and black infants (31.6 minutes [-5.9, 69.1]). Night sleep duration also increased less for infants with lower maternal education and household income. Asian infants had more frequent night awakenings. Adjustment for maternal education and household income attenuated all observed day and night sleep duration differences other than in Asians, where persistently reduced nighttime sleep at 6 months was observed. CONCLUSIONS: Racial/ethnic differences in sleep emerge in early infancy. Night and 24-hour sleep durations increase less in Hispanic and black infants compared to white infants, with differences largely explained by SES.

Associations between parent-reported and objectively measured sleep duration and timing in infants at age 6 months.

STUDY OBJECTIVES: To compare the estimates of sleep duration and timing from survey, diary, and actigraphy in infants at age 6 months, overall and by select demographics and other factors. METHODS: In total, 314 infants participating in the Rise & SHINE (Sleep Health in Infancy & Early Childhood study) cohort in Boston, MA, USA, wore an actigraph on their left ankle for 7 days. Parents concurrently completed a sleep diary and the expanded version of the Brief Infant Sleep Questionnaire. Concordance between parent-reported and objective sleep estimates was assessed using Bland-Altman plots, Spearman's rank correlations, intraclass correlations, and linear regression models. RESULTS: Mean infant age was 6.4 (0.6 SD) months; 51% were female and 42% were Non-Hispanic white. Mean total sleep duration using actigraphy was 526 (67 SD) minutes per night, 143 (42 SD) minutes per day, and 460 (100 SD) minutes during the longest nighttime sleep period. Relative to actigraphy, parent-completed survey and diary overestimated total day (by 29 and 31 minutes, respectively) and night sleep duration (67 and 43 minutes, respectively) and underestimated the longest sleep (58 minutes), with the highest agreement for sleep onset and offset timing (differences < 30 minutes). There was a tendency toward greater bias among short- and long-sleeping infants. Self-reporting bias for diary-measured longest nighttime sleep and total night sleep duration was higher in infants of parents reporting a problem with their baby's night awakenings and in low-income families, respectively. CONCLUSIONS: Our findings underscore the need to be cautious when comparing findings across studies using different sleep assessment methods.

Nightly sleep duration, fragmentation, and quality and daily risk of migraine.

OBJECTIVE: To test the hypotheses that insufficient duration, high fragmentation, and poor sleep quality are temporally associated with migraine onset on the day immediately following the sleep period (day 0) and the following day (day 1). METHODS: In this prospective cohort study of 98 adults with episodic migraine, participants completed twice-daily electronic diaries on sleep, headaches, and other health habits, and wore wrist actigraphs for 6 weeks. We estimated the incidence of migraine following nights with short sleep duration, high fragmentation, or low quality compared to nights with adequate sleep with conditional logistic regression models stratified by participant and adjusted for caffeine intake, alcohol intake, physical activity, stress, and day of week. RESULTS: Participants were a mean age of 35.1 ± 12.1 years. We collected 4,406 days of data, with 870 headaches reported. Sleep duration ≤6.5 hours and poor sleep quality were not associated with migraine on day 0 or day 1. Diary-reported low efficiency was associated with 39% higher odds of headache on day 1 (odds ratio [OR] 1.39, 95% confidence interval [CI] 1.06-1.81). Actigraphic-assessed high fragmentation was associated with lower odds of migraine on day 0 (wake after sleep onset >53 minutes, OR 0.64, 95% CI 0.48-0.86; efficiency ≤88%, OR 0.74, 95% CI 0.56-0.99). CONCLUSION: Short sleep duration and low sleep quality were not temporally associated with migraine. Sleep fragmentation, defined by low sleep efficiency, was associated with higher odds of migraine on day 1. Further research is needed to understand the clinical and neurobiologic implications of sleep fragmentation and risk of migraine.

The Use of Actigraphy Differentiates Sleep Disturbances in Active and Inactive Crohn's Disease.

BACKGROUND: Sleep disturbances (SDs) are commonly reported in patients with Crohn's disease (CD). Several survey instruments assessing subjective measures of insufficient sleep have identified SDs in subjects with CD. However, there are limited data on objective measures of SDs in these patients as they relate to disease activity. In this prospective cross-sectional study, we compared objective estimates of sleep obtained using multiday wrist actigraphy in individuals with CD with varying disease activity. METHODS: Eighty patients with a diagnosis of CD were recruited to take part in the study. Participants were stratified by disease activity into remission, mild disease, and moderate to severe disease groups using the Harvey-Bradshaw Index and C-reactive protein levels. Participants were excluded on the basis of significant comorbidity (Charlson Comorbidity Index ≥3), a known history of a sleep disorder, or the concomitant use of systemic corticosteroids. Participants completed surveys, including the PROMIS-SD Short Form 8a, the Epworth Sleepiness Scale, and the Women's Health Initiative Insomnia Rating scale, and were provided with an accelerometer that estimated sleep-wake patterns over 7 days. Comparisons of actigraphic sleep parameters were performed between disease activity groups. Multivariate logistic regression analyses were performed using covariates determined a priori to have an association with sleep disturbance in CD through a review of the literature. RESULTS: Of the 80 participants enrolled in the study, 72 completed 5 days of actigraphy data: 28 subjects in remission, 22 subjects with mild disease activity, and 22 subjects with moderate to severe disease activity. Self-reported sleep characteristics assessed by questionnaires were similar between groups. By actigraphy, individuals with moderate to severe CD spent a significantly longer time awake after falling asleep compared with subjects with remissive disease or compared with subjects with mild disease (65.8 minutes vs 44.3 minutes and 49.1 minutes, respectively; each P < 0.05). Individuals with moderate to severe CD had significantly lower sleep efficiency compared with those with remissive CD (86.6% vs 89.9%; P = 0.03). In the multivariate analyses, moderate to severe CD disease activity was significantly associated with an increased amount of fragmented sleep (odds ratio [OR], 3.70; 95% confidence interval [CI], 1.23-11.32; P = 0.02; WASO ≥ 60 minutes). Moreover, the use of controlled substances was associated with poor sleep efficiency (OR, 3.86; 95% CI, 1.01-14.7; P = 0.04; SE ≤ 85.5%). CONCLUSIONS: This is the first study to objectively quantify disturbed sleep using wrist actigraphy in adults with CD with varying disease activity. Wrist actigraphy may serve as a useful modality for discerning SD in subjects with active vs remissive disease that is not evident with questionnaires alone. Although we determined that disease severity is a significant factor that leads to SDs in CD, larger studies using these objective measures may help determine the contribution of other factors.

Association of Daily Rest-Activity Patterns With Adiposity and Cardiometabolic Risk Measures in Teens.

PURPOSE: Emerging data indicate that the timing and rhythms of energetic behaviors may influence metabolism and obesity risk. Our aim was to derive diurnal rest-activity patterns from actigraphy in adolescents and analyze associations with adiposity measures and cardiometabolic risk factors. METHODS: Adolescents in the Project Viva cohort wore a wrist actigraph over 7 days. We derived markers of daily rest-activity patterns from actigraphy using nonparametric models, generating measurements of relative amplitude (RA). RA reflects the normalized difference in activity measured during the most active 10-hour period and the least active 5-hour period, averaged over multiple 24-hour periods. Using multivariable-adjusted linear regression models, we estimated associations of RA and its components with markers of adiposity (body mass index, waist circumference, skinfolds, dual-energy X-ray absorptiometry fat mass) and cardiometabolic health (cardiometabolic risk score, derived as the mean of five sex-specific internal z-scores for waist circumference, systolic blood pressure, high-density lipoprotein cholesterol scaled inversely, and log-transformed triglycerides and homeostatic model assessment of insulin resistance). RESULTS: A total of 778 adolescents provided at least 5 days of valid actigraphy data. The average age was 13.2 (±.9) years, 52% were female, and the average RA was .9 (±.1). A higher RA reflecting higher activity during wakefulness and lower activity during the night was associated with more favorable indices of adiposity (e.g., -.35 kg/m2 lower body mass index per each .04 units increment of RA; 95% confidence interval: -.60 to -.09). CONCLUSIONS: In this large sample of adolescents, a higher RA emerged as a novel biomarker, associated with more favorable cardiometabolic profiles.

Associations Between Timing of Meals, Physical Activity, Light Exposure, and Sleep With Body Mass Index in Free-Living Adults.

BACKGROUND: This study tested if the timing of meals, physical activity, light exposure, and sleep cluster within individuals and are associated with body mass index (BMI) in a sample of free-living adults (N = 125). METHODS: Data were collected between November 2015 and March 2016 at the University of California, San Diego, Children's Hospital of Philadelphia, and Washington University in St Louis. Height and weight were measured, and BMI (kg/m2) was calculated. Sleep timing was estimated using actigraphy, and timing of meals, physical activity, and light exposure were self-reported using a smartphone application. General linear models estimated the mean BMI across time categories of behaviors, adjusting for covariates. A latent class analysis was used to identify patterns of timing variables that clustered within individuals and test for associations between identified patterns and BMI. RESULTS: Later exposure to outdoor light was associated with a lower BMI (P trend < .01). The timing of other behaviors was not independently associated with BMI. The latent class analysis identified 2 distinct groups related to behavioral timing, reflecting an "early bird" and "night owl" phenotype. These phenotypes were not associated with BMI (P > .05). CONCLUSION: Timing of exposures to light, meals, sleep, and physical activity were not strongly associated with BMI in this sample.

Zeitgebers and their association with rest-activity patterns.

Zeitgebers such as light, eating and physical activity provide input to the circadian clock. Chronic circadian misalignment is associated with significant adverse health effects. An improved understanding of the impact of the timing of zeitgebers on the stability of 24-hour rest-activity rhythm in free-living settings may identify behavioural and environmental intervention targets. A total of 133 healthy adults, aged 21-60 years, wore a wrist actigraph for 7 consecutive days. We applied a non-parametric analysis to activity counts to derive rest-activity patterns. We administered a questionnaire through a smartphone app to collect self-reported timing of light exposure, eating episodes and physical activity. To assess the relationship between timing exposures (first and last exposure to outdoor light, first exposure to indoor light, last eating episode, first eating episode, morning physical activity proportion, evening physical activity proportion) and rest-activity or sleep outcomes (bedtimes, total sleep time, inter-daily stability, intra-daily variability, L5 and M10 midpoint), we first calculated Spearman correlations, using the false discovery rate method to control for multiple comparisons. From those significant associations, we then fit regression models adjusting for age, sex, race, household income, education level, study site, body mass index, as well as physical activity. Finally, we tested for interaction between chronotype and each timing-related exposure and stratified the analysis by morning type. All zeitgebers, except for evening physical activity proportion, were correlated with at least four of the seven sleep and rest-activity outcomes. In adjusted analysis, later timing of first (after 6:30 to 7:45 AM versus earlier) and last exposure to indoor light (after 11:00 PM versus earlier) and first (after 7:45-9:45 AM versus earlier) and last eating episode (after 8:00-09:00 PM versus earlier) were associated with a shift of 0.60-1.39 hours to later bedtimes, M10 and L5 midpoints (i.e. timing of peak activities or inactivities). Later timing of first exposure to outdoor light (after 09:30 AM versus earlier) was also associated with 0.51 (95% CI: 0.19 to 0.83) hours longer total sleep time. Higher morning physical activity proportion (> 33%) was associated with 0.95 (95% CI: -1.38 to -0.53) hours earlier in-bed time and 0.69 (95% CI: -1.14 to -0.24) hours earlier out-of-bed time, 0.92 (95% CI: -1.41 to -0.42) hours earlier M10 and 0.96 (95% CI: -1.42 to -0.49) min earlier L5 midpoint. The results did not change substantially with further adjustment for total activity. There was a significant interaction between morning chronotype and first eating episode with rest-activity patterns (p < 0.05), with first eating episode associating with timing of activities only in non-morning type adults. Timing of zeitgebers was associated with sleep and rest-activity patterns, including bedtimes, L5 and M10 midpoint. Future research should evaluate the impact of manipulating zeitgebers on both circadian rhythms and health outcomes.

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

OBJECTIVES: Actigraphy is widely used to estimate sleep-wake time, despite limited information regarding the comparability of different devices and algorithms. We compared estimates of sleep-wake times determined by two wrist actigraphs (GT3X+ versus Actiwatch Spectrum [AWS]) to in-home polysomnography (PSG), using two algorithms (Sadeh and Cole-Kripke) for the GT3X+ recordings. SUBJECTS AND METHODS: Participants included a sample of 35 healthy volunteers (13 school children and 22 adults, 46% male) from Boston, MA, USA. Twenty-two adults wore the GT3X+ and AWS simultaneously for at least five consecutive days and nights. In addition, actigraphy and PSG were concurrently measured in 12 of these adults and another 13 children over a single night. We used intraclass correlation coefficients (ICCs), epoch-by-epoch comparisons, paired t-tests, and Bland-Altman plots to determine the level of agreement between actigraphy and PSG, and differences between devices and algorithms. RESULTS: Each actigraph showed comparable accuracy (0.81-0.86) for sleep-wake estimation compared to PSG. When analyzing data from the GT3X+, the Cole-Kripke algorithm was more sensitive (0.88-0.96) to detect sleep, but less specific (0.35-0.64) to detect wake than the Sadeh algorithm (sensitivity: 0.82-0.91, specificity: 0.47-0.68). Total sleep time measured using the GT3X+ with both algorithms was similar to that obtained by PSG (ICC=0.64-0.88). In contrast, agreement between the GT3X+ and PSG wake after sleep onset was poor (ICC=0.00-0.10). In adults, the GT3X+ using the Cole-Kripke algorithm provided data comparable to the AWS (mean bias=3.7±19.7 minutes for total sleep time and 8.0±14.2 minutes for wake after sleep onset). CONCLUSION: The two actigraphs provided comparable and accurate data compared to PSG, although both poorly identified wake episodes (i.e., had low specificity). Use of actigraphy scoring algorithm influenced the mean bias and level of agreement in sleep-wake times estimates. The GT3X+, when analyzed by the Cole-Kripke, but not the Sadeh algorithm, provided comparable data to the AWS.

Practical considerations in using accelerometers to assess physical activity, sedentary behavior, and sleep.

Increasingly, behavioral and epidemiological research uses activity-based measurements (accelerometry) to provide objective estimates of physical activity, sedentary behavior, and sleep in a variety of study designs. As interest in concurrently assessing these domains grows, there are key methodological considerations that influence the choice of monitoring instrument, analysis algorithm, and protocol for measuring these behaviors. The purpose of this review is to summarize evidence-guided information for 7 areas that are of importance in the design and interpretation of studies using actigraphy: (1) choice of cut-points; (2) impact of epoch length; (3) accelerometer placement; (4) duration of monitoring; (5) approaches for distinguishing sleep, nonwear times, and sedentary behavior; (6) role for a sleep and activity diary; and (7) epidemiological applications. Recommendations for future research are outlined and are intended to enhance the appropriate use of accelerometry for assessing physical activity, sedentary behavior, and sleep behaviors in research studies.

Short-term testosterone manipulations modulate visual recognition memory and some aspects of emotional reactivity in male rhesus monkeys.

The role of testosterone (T) in modulating cognitive function and emotion in men remains unclear. The paucity of animal studies has likely contributed to the slow progress in this area. In particular, studies in nonhuman primates have been lacking. Our laboratory has begun to address this issue by pharmacologically manipulating T levels in intact male rhesus monkeys, using blind, placebo-controlled, crossover designs. We previously found that T-suppressed monkeys receiving supraphysiological T for 4 weeks had lower visual recognition memory for long delays and enhanced attention to videos of negative social stimuli (Lacreuse et al., 2009, 2010) compared to when treated with oil. To further delineate the conditions under which T affects cognition and emotion, the present study focused on the short-term effects of physiological T. Six intact males were treated with the gonadotropin-releasing hormone antagonist degarelix (3 mg/kg) for 7 days and received one injection of T enanthate (5 mg/kg) followed by one injection of oil vehicle 7 days later (n=3), or the reverse treatment (n=3). Performance on two computerized tasks, the Delayed-non-matching-to-sample (DNMS) with random delays and the object-Delayed Recognition Span test (object-DRST) and one task of emotional reactivity, an approach/avoidance task of negative, familiar and novel objects, was examined at baseline and 3-5 days after treatment. DNMS performance was significantly better when monkeys were treated with T compared to oil, independently of the delay duration or the nature (emotional or neutral) of the stimuli. Performance on the object-DRST was unaffected. Interestingly, subtle changes in emotional reactivity were also observed: T administration was associated with fewer object contacts, especially on negative objects, without overt changes in anxious behaviors. These results may reflect increased vigilance and alertness with high T. Altogether, the data suggest that changes in general arousal may underlie the beneficial effects of T on DNMS performance. This hypothesis will require further study with objective measures of physiological arousal.