Non-wear or sleep? Evaluation of five non-wear detection algorithms for raw accelerometer data

ABSTRACT

Detection of non-wear periods is an important step in accelerometer data processing. This study evaluated five non-wear detection algorithms for wrist accelerometer data and two rules for non-wear detection when non-wear and sleep algorithms are implemented in parallel. Non-wear algorithms were based on the standard deviation (SD), the high-pass filtered acceleration, or tilt angle. Rules for differentiating sleep from non-wear consisted of an override rule in which any overlap between non-wear and sleep was deemed non-wear; and a 75% rule in which non-wear periods were deemed sleep if the duration was < 75% of the sleep period. Non-wear algorithms were evaluated in 47 children who wore an ActiGraph GT3X+ accelerometer during school hours for 5 days. Rules for differentiating sleep from non-wear were evaluated in 15 adults who wore a GeneActiv Original accelerometer continuously for 24 hours. Classification accuracy for the non-wear algorithms ranged between 0.86–0.95, with the SD of the vector magnitude providing the best performance. The override rule misclassified 37.1 minutes of sleep as non-wear, while the 75% rule resulted in no misclassification. Non-wear algorithms based on the SD of the acceleration signal can effectively detect non-wear periods, while application of the 75% rule can effectively differentiate sleep from non-wear when examined concurrently.     

运动员午睡睡眠惯性研究

通过实验研究运动员午睡的影响作用和睡眠惯性的持续时间．结果显示,1h午睡后,运动员的大脑机能状态、神经-肌肉兴奋性和心境状态等指标在醒后0．5h仍处于较低水平。而在醒后1h却显著提高,且超过睡前基线水平;而睡眠惯性的持续时间要长于0．5h,在1h左右基本消退．     

Lower-body compression garments worn following exercise improves perceived recovery but not subsequent performance in basketball athletes

ABSTRACT

This study examined the effects of lower-body compression garments on perceived recovery and subsequent performance in basketball athletes. In a parallel-group design, 30 recreational, male basketball athletes were randomly allocated to either a control (CON, n = 15, loose-fitting clothing) or experimental group (COMP, n = 15, compression garments) for 15 h following fatigue-inducing, basketball-specific exercise in the evening (1600-1800 h). Perceptual measures of fatigue and muscle soreness, as well as physical performance tests (sprints, jumps and agility), were performed pre-exercise, post-exercise, and post-recovery (15 h following exercise). Subjective and objective measures of sleep were recorded following the exercise trial. There were non-significant (p > 0.05), unclear-trivial differences between groups for all performance measures. Perceived post-recovery fatigue (d = ?1.27, large) and muscle soreness (d = ?1.61, large) were significantly lower in COMP compared to CON (p < 0.05). COMP exhibited better perceived sleep quality (d = 0.42, small, p = 0.18) than CON, with an unclear difference in sleep duration between groups (p > 0.05). Wearing lower-body compression garments overnight improved perceived fatigue and muscle soreness, but had negligible effects on subsequent physical performance in basketball athletes. Future research should focus on longer periods of compression wear following fatiguing exercise.     

Sleep quality improved following a single session of moderate-intensity aerobic exercise in older women: Results from a pilot study

BackgroundPoor sleep quality is associated with adverse effects on health outcomes. It is not clear whether exercise can improve sleep quality and whether intensity of exercise affects any of the effects.MethodsFifteen healthy, non-obese (body mass index = 24.4 ± 2.1 kg/m², mean ± SD), sedentary (<20 min of exercise on no more than 3 times/week) older women (66.1 ± 3.9 years) volunteered for the study. Peak oxygen consumption (VO_2peak) was evaluated using a graded exercise test on a treadmill with a metabolic cart. Following a 7-day baseline period, each participant completed two exercise sessions (separated by 1 week) with equal caloric expenditure, but at different intensities (60% and 45% VO_2peak, sequence randomized) between 9:00 and 11:00 am. A wrist ActiGraph monitor was used to assess sleep at baseline and two nights following each exercise session.ResultsThe average duration of the exercise was 54 and 72 min, respectively at 60% (moderate-intensity) and 45% VO_2peak (light-intensity). Wake time after sleep onset was significantly shorter (p = 0.016), the number of awakenings was less (p = 0.046), and total activity counts were lower (p = 0.05) after the moderate-intensity exercise compared to baseline no-exercise condition.ConclusionOur data showed that a single moderate-intensity aerobic exercise session improved sleep quality in older women.     

Depression,Fatigue, and Pre-Sleep Arousal: A Mediation Model

Fatigue is a common and debilitating symptom of clinical depression; however, the causes are not well understood. The present study was designed to test the hypotheses that subjective sleep, objective sleep, and arousal in the pre-sleep state would mediate the relationship between depression status and fatigue. Sleep, pre-sleep arousal, and fatigue were assessed in 21 depressed and 37 never-depressed undergraduates. Results showed that pre-sleep arousal was a significant partial mediator of the relationship between depression status and fatigue. These results indicate that arousal in the pre-sleep state deserves further attention as a potential antecedent to fatigue in clinically depressed undergraduates.     

睡眠影响记忆巩固的研究进展

学习后睡眠有利于记忆巩固,学习的类型不同,睡眠依赖的记忆巩固机制可能也有所不同,涉及到不同脑区在不同的睡眠时相的生理功能。睡眠有助于长时程增强（long-term potentiation,LTP）的形成,进而促进记忆的巩固。总睡眠剥夺、快动眼睡眠剥夺、片段性睡眠可以通过不同的分子生物学机制损伤记忆巩固。     

"空竹"运动对老年人情绪、睡眠健康的影响

研究民族传统项目“抖空竹”对老年人心理与睡眠健康的影响,通过对参加空竹运动前后的6 0名老年人睡眠质量及情绪进行调查分析。结果显示,参加“空竹”运动后的老年人匹兹堡睡眠质量指数与运动前相比有显著性差异(P <0 .0 5 ) ;焦虑和抑郁分值显著小于运动前,且有非常显著性变化(P <0 .0 1)。由此表明,“空竹”运动能有效地改善老年人焦虑和抑郁症状,起到改善和提高老年人睡眠质量的效果,并对老年人的心理健康起到积极的作用。     

Combined effects of sleep deprivation and strenuous exercise on cognitive performances during The North Face® Ultra Trail du Mont Blanc® (UTMB®)

This study investigated the effects of combined sleep deprivation and strenuous exercise on cognitive and neurobehavioral performance among long-distance runners completing one of the most difficult ultramarathons in the world. Seventeen runners participated. Each had a wrist-worn actigraph throughout the race to record their sleep time. In addition, each individual’s performance in 10-min response-time tests before and after the race was recorded and a questionnaire enabled participants to report any difficulties they experienced during the competition. During race completion times of 27 to 44 h, combined acute lack of sleep (12 ± 17 min of rest during the race) and strenuous exercise (168.0 km) had marked adverse effects on cognitive performances ranging from mere lengthening of response time to serious symptoms such as visual hallucinations. This study suggests that regardless of rest duration and time in race, cognitive performances of ultramarathoners are adversely affected.     

Logarithmic Growth Algorithm of Sleep Mode of Broadband Mobile Access Terminal

The sleep mode which works upon low arrival traffic is introduced in IEEE802.16e standard to reduce the power consumption of the mobile access terminal. Due to the rapid growth in the sleep interval in the exponential growth algorithm prescribed in IEEE802.16e, the power saving efficiency of the mobile access terminal is limited and the average delay time of receiving data frames is prolonged when the arrival rate of data frames is low. To obtain lower power consumption and shorter average delay time, the l...