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STUDY OBJECTIVE - To describe sleep duration and quality in the first month postpartum and compare the sleep of women who exclusively breastfed at night to those who used formula.
METHODS - We conducted a longitudinal study in a predominantly low-income and ethnically diverse sample of 120 first-time mothers. Both objective and subjective measures of sleep were obtained using actigraphy, diary, and self-report data. Measures were collected in the last month of pregnancy and at one month postpartum. Infant feeding diaries were used to group mothers by nighttime breastfeeding behavior.
RESULTS - Mothers who used at least some formula at night (n = 54) and those who breastfed exclusively (n = 66) had similar sleep patterns in late pregnancy. However, there was a significant group difference in nocturnal sleep at one month postpartum as measured by actigraphy. Total nighttime sleep was 386 ± 66 minutes for the exclusive breastfeeding group and 356 ± 67 minutes for the formula group. The groups did not differ with respect to daytime sleep, wake after sleep onset (sleep fragmentation), or subjective sleep disturbance at one month postpartum.
CONCLUSION - Women who breastfed exclusively averaged 30 minutes more nocturnal sleep than women who used formula at night, but measures of sleep fragmentation did not differ. New mothers should be encouraged to breastfeed exclusively since breastfeeding may promote sleep during postpartum recovery. Further research is needed to better understand how infant feeding method affects maternal sleep duration and fragmentation.
CITATION - Doan T; Gay CL; Kennedy HP; Newman J; Lee KA. Nighttime breastfeeding behavior is associated with more nocturnal sleep among first-time mothers at one month postpartum.
PURPOSE - A previous-day recall (PDR) may be a less error-prone alternative to traditional questionnaire-based estimates of physical activity and sedentary behavior (e.g., past year), but the validity of the method is not established. We evaluated the validity of an interviewer administered PDR in adolescents (12-17 yr) and adults (18-71 yr).
METHODS - In a 7-d study, participants completed three PDR, wore two activity monitors, and completed measures of social desirability and body mass index. PDR measures of active and sedentary time was contrasted against an accelerometer (ActiGraph) by comparing both to a valid reference measure (activPAL) using measurement error modeling and traditional validation approaches.
RESULTS - Age- and sex-specific mixed models comparing PDR to activPAL indicated the following: 1) there was a strong linear relationship between measures for sedentary (regression slope, β1 = 0.80-1.13) and active time (β1 = 0.64-1.09), 2) person-specific bias was lower than random error, and 3) correlations were high (sedentary: r = 0.60-0.81; active: r = 0.52-0.80). Reporting errors were not associated with body mass index or social desirability. Models comparing ActiGraph to activPAL indicated the following: 1) there was a weaker linear relationship between measures for sedentary (β1 = 0.63-0.73) and active time (β1 = 0.61-0.72), (2) person-specific bias was slightly larger than random error, and (3) correlations were high (sedentary: r = 0.68-0.77; active: r = 0.57-0.79).
CONCLUSIONS - Correlations between the PDR and the activPAL were high, systematic reporting errors were low, and the validity of the PDR was comparable with the ActiGraph. PDR may have value in studies of physical activity and health, particularly those interested in measuring the specific type, location, and purpose of activity-related behaviors.
STUDY OBJECTIVES - Patients with postural tachycardia syndrome (POTS) commonly complain of fatigue, unrefreshing sleep, daytime sleepiness and diminished quality of life. The study objective was to assess sleep quality in POTS patients using wrist actigraphy.
DESIGN - Prospective study with control group.
METHODS - Patients with POTS (n = 36) and healthy subjects (n = 36) completed a detailed sleep log and actigraphy for 7 days.
RESULTS - Compared with healthy subjects, POTS patients have more self-reported problems including days with restless sleep (53 ± 30% vs. 21 ± 20%; P<0.001) and tiredness (75 ± 23% vs. 39 ± 27%; P<0.001). Using actigraphy, POTS patients have lower sleep efficiency (73 ± 13% vs. 79 ± 6%; P = 0.01). Actigraphy determined sleep onset latency (SOL) did not vary significantly in the two groups, but subjective SOL was higher in POTS patient (56 ± 66 min vs. 1 3 ± 9 min; P = 0.001). In POTS patients, there was a significant correlation between subjective complaints of tiredness and actigraphic sleep efficiency (Rs = -0.36; R(2) = 0.15; P = 0.01), significant correlations between actigraphic SOL and upright norepinephrine levels (P = 0.040), and between wake after sleep onset and standing heart rate (P = 0.02).
CONCLUSIONS - POTS patients have more sleep-related symptoms and poor sleep efficiency. The pattern of subjective vs. objective SOL mismatch is suggestive of sleep-state misperception. High norepinephrine correlated with actigraphic SOL, and this activation of the stress system may contribute significantly to a hyperarousal state with consequent insomnia, poor mental and physical health in POTS patients.
Copyright © 2013 Elsevier B.V. All rights reserved.
PURPOSE - The objective of this study is to determine the effect of body mass index (BMI) on level of agreement between six previously established prediction equations for three commonly used accelerometers to predict summary measures of energy expenditure (EE) in youth.
METHODS - One hundred and thirty-one youth between the ages of 10-17 yr and BMI from 15 to 44 kg·m were outfitted with hip-worn ActiGraph GT1M (Pensacola, FL), Actical (MiniMiter/Respironics, Bend, OR), and RT3 (StayHealthy, Monrovia, CA) accelerometers and spent approximately 24 h in a whole-room indirect calorimeter while performing structured and self-selected activities. Five commonly used regression and one propriety equations for each device were used to predict the minute-to-minute EE (normalized to METs), daily physical activity level (PAL), and time spent in sedentary, light, moderate, and vigorous physical activity intensity categories. The calculated values were compared with criterion measurements obtained from the room calorimeter.
RESULTS - All predictive equations, except RT3, significantly over- or underpredicted daily PAL (P < 0.001), with large discrepancies observed in the estimate of sedentary and light activity. Discrepancies between actual and estimated PAL ranged from 0.05 to 0.68. In addition, BMI represented a modifier for two ActiGraph predictive equations (AG1 and AG2), affecting the accuracy of physical activity-related EE predictions.
CONCLUSION - ActiGraph (AG3) and the RT3 closely predicted overall PAL (within 4.2% and 6.8%, respectively) as a group. When adjusting for age, sex, and ethnicity, Actical (AC1 and AC2) and ActiGraph (AG3) were not influenced by BMI. However, a gap between some hip-worn accelerometer predictive and regression equations was demonstrated compared with both criterion measurement and each other, which poses a potential difficulty for interstudy (e.g., different accelerometers) and intrastudy (e.g., BMI and adiposity) comparisons.
Children with neurodevelopmental disorders may have difficulty tolerating devices that monitor sleep, presenting challenges in measuring sleep disturbances in this population. Although wrist actigraphy has advantages over polysomnography, some children remain unable to tolerate wrist placement. This study piloted an alternative site for actigraphy in 8 children with autism, ages 6-10 years. Results are presented from the 2 locations (custom pocket shoulder location and wrist location) using Bland-Altman limits of agreement and other statistical measures to compare sleep onset latency, total sleep time, sleep efficiency, and wake after sleep onset. The use of an alternative actigraphy site for children with autism, who have difficulty tolerating actigraphy placement, appears promising and worthy of further study.
BACKGROUND - Sleep concerns are common in children with Angelman syndrome, with 20-80% of individuals having a decreased sleep need and/or abnormal sleep-wake cycles. The impact of these sleep behaviours on parental sleep and stress is not known.
METHOD - Through the use of standardised questionnaires, wrist actigraphy and polysomnography, we defined the sleep behaviours of 15 children/adolescents with Angelman syndrome and the association of the child/adolescents sleep behaviours on parental sleep behaviours and parental stress.
RESULTS - Both children/adolescents and their parents exhibited over 1 h of wake time after sleep onset and fragmented sleep. Prolonged sleep latency in the child was associated with parent insomnia and daytime sleepiness. Additionally, variability in child total sleep time was associated with parental stress.
CONCLUSIONS - Poor sleep in children/adolescents with Angelman syndrome was associated with poor parental sleep and higher parental stress. Further work is warranted to identify the underlying causes of the poor sleep, and to relate these findings to daytime functioning, behaviour and the family unit.
© 2011 The Authors. Journal of Intellectual Disability Research © 2011 Blackwell Publishing Ltd.
PURPOSE - In large epidemiologic studies, physical activity (PA) is often assessed using PA questionnaires (PAQ). Because available PAQ may not capture the full range of PA in which urban Chinese adults engage, a PAQ was developed for this purpose. We examined the validity of this PAQ and the 1-yr stability of PA in 545 urban Shanghai adults.
METHODS - The PAQ was interview-administered twice, approximately 1 yr apart, and participants also wore an accelerometer and completed a PA-log for seven consecutive days every 3 months during the same year. The intraclass correlation coefficient (ICC) was used to evaluate the stability of PA across questionnaire administrations, and Spearman correlation coefficients (ρ) and mean differences and 95% limits of agreement were used to examine the validity of the questionnaire compared against accelerometry and the PA-log.
RESULTS - When measured by accelerometry, estimates of time spent in moderate-to-vigorous PA were lower and estimates of time spent sedentary were higher than when self-reported on the PAQ (P < 0.001). Total PA (ICC = 0.65) and PA domains (ICC = 0.45-0.85) showed moderate to high stability across PAQ administrations. Total PA (ρ = 0.30), moderate-to-vigorous activity (ρ = 0.17), light activity (ρ = 0.36), and sedentary behavior (ρ = 0.16) assessed by PAQ and by accelerometry were significantly and positively correlated, and correlations of the PAQ with the PA-log (ρ = 0.36-0.85) were stronger than those observed with accelerometry.
CONCLUSIONS - The PAQ significantly overestimated time spent in moderate-to-vigorous activity and underestimated time spent in light activity and sedentary behavior compared with accelerometry, but it performed well at ranking participants according to PA level.