Chronic Low Quality Sleep Impairs Postural Control in Healthy Adults

Evaluation of 2 different wrist actigraphy devices in the adult population

STUDY OBJECTIVES

Actigraphy devices are used in sleep medicine. The Actiwatch 2 (Philips Respironics) was an example of a frequently used device in this field. Nevertheless, the discontinuation of this device has led to an increased necessity for the implementation of other available actigraphy methods capable of providing objective information. The objective of this study was to assess the performance of the new ActTrust 2 compared to the Actiwatch 2 model.

METHODS

This observational prospective study included 9 participants (77.760 activity logs) who were monitored for 7 days using 2 actigraphy wrist devices (ActTrust 2 and Actiwatch 2) simultaneously. The following variables were evaluated: midline estimating statistic of rhythm, amplitude, and acrophase; intradaily variability; interdaily stability; relative amplitude; and the mean of 5 consecutive hours with the lowest activity and the 10 consecutive hours with the highest activity. Furthermore, total sleep time, time in bed, sleep efficiency, sleep onset latency, wake after sleep onset, and awakenings were also included.

RESULTS

Actigraphy models indicated statistically significant differences in activity levels. Regarding the analysis of circadian rest-activity rhythms, 10 consecutive hours with the highest activity, midline estimating statistic of rhythm, and amplitude also exhibited these differences. Furthermore, the analysis of sleep-wakefulness revealed significant differences in the sleep onset latency and the number of awakenings.

CONCLUSIONS

The ActTrust 2 and Actiwatch 2 models showed equivalent results in measuring circadian rest-activity rhythm and sleep. However, caution is advised when interpreting parameters such as midline estimating statistic of rhythm, amplitude, sleep onset latency, awakenings, and 10 consecutive hours with the highest activity variables.

CITATION

Henríquez-Beltrán M, Benítez ID, Juez-Garcia I, et al. Evaluation of 2 different wrist actigraphy devices in the adult population. J Clin Sleep Med. 2025;21(5):805-812.

Circadian disruption is associated with altered postural control in aged individuals under eye closed condition

Background

Sleep loss is reported to affect postural control. However, the relationship between increased postural sway and the circadian rhythm (CR) remains unclear.

Objectives

To assess performance in the postural control test in aged individuals with an abnormal CR.

Methods

This cross-sectional observational study included two groups of participants: those at high risk of falling (HFR) and those at low risk of falling (LFR), which was determined by the clinical cut-off score for the sway path with open eyes. Each participant wore an ActiGraph device on their non-dominant hand for 5-7 days. A non-parametric analysis of CR variables, including interdaily stability (IS), intraday variability (IV), relative amplitude (RA), interdaily coefficient of variation (ICV), etc., was used to evaluate the postural stability with a posturographic platform during a 30-s static balance test under the eyes closed (EC) and eyes open (EO) condition.

Results

Individuals in the HFR group demonstrated significantly higher scores in the Downton fall risk index (DFRI), higher ICV, and lower IS and M10 activity counts than the LFR group. Linear regression analysis revealed that under the EO condition, there was no association between postural control and CR disruption; however, under the EC condition, L5 was positively associated with variables reflecting an increase in postural sway.

Conclusion

Increased postural sway was found to be associated with CR disruption in aged adults under the EC condition.

Poor Sleep Quality Worsens Static and Dynamic Balance Control in Individuals With Chronic Low Back Pain: A Cross-Sectional Study

Objective: To investigate the influence of sleep quality and associated factors on balance control in individuals with chronic low back pain (CLBP). Methods: 85 participants (mean age 33.2 ± 12.5 years) with CLBP were recruited. Physical and emotional well-beings were evaluated using a battery of questionnaires. Sleep quality over the last month was assessed using the Pittsburgh Sleep Quality Index (PSQI). Participants were dichotomized into the good sleep quality (GSQ) and poor sleep quality (PSQ) groups if their PSQI scores were ≤ 5 and > 5, respectively. Balance control was measured using the one-leg stance with eyes closed and Y-balance test. Results: The GSQ group included 37 participants, while the PSQ group comprised 48 participants. After controlling for confounds (including gender, age, disability, anxiety, depression, and fear avoidance beliefs), participants with PSQ displayed significantly poorer performance in the one-leg stance with eyes closed and lower normalized posteromedial, posterolateral, and composite scores of the Y-balance test compared with participants with GSQ. Additionally, sleep quality accounted for 16.9%-24.9% of the variance in balance control, while age explained an additional 5.2%-13.2% of the variance. Additionally, higher levels of physical disability and anxiety were associated with poorer balance control. Conclusions: Individuals with concurrent CLBP and PSQ exhibit significantly worse balance control than those with CLBP alone. Future studies should investigate whether improving sleep quality, physical disability, and anxiety can enhance balance in individuals with CLBP.

Exploring the Effects of Sensorimotor Training and Relaxation Therapy on Postural Control, Balance, Sleep, and Stress in Sedentary Young Adults: Rationale, Design, and Methodology

Postural control (PC) and sleep are critical in several aspects of health. Poor sleep negatively influences PC and balance, which is necessary for performing various tasks, from reaching to mobility. Moreover, sleep disturbances and consequent PC and balance deterioration are associated with job accidents, traffic accidents, falls, and injuries. Healthy adults who have inadequate sleep show a decline in optimal functioning, even in the absence of medical illnesses. This suggests that getting enough sleep, both in duration and quality, is essential to maintain optimal health. Moreover, inadequate sleep has also been observed to have a bidirectional relationship with stress levels. However, there is insufficient evidence regarding the impact of non-pharmacological treatments to improve PC, sleep, and stress in the sedentary young adult (YA) population. This article describes the protocol for a study to investigate the effects of sensorimotor training and relaxation therapy on various static and dynamic PC tests, balance measures, and subjective and objective indices of sleep and stress among sedentary YAs with impaired sleep quality. The protocol is also designed to evaluate the effect of these therapies on fatigue, salivary cortisol levels, anxiety, and depression. Methods for assessing the sleep architecture, static and dynamic PC, balance, and stress are described along with the methods of scoring with the primary goal of providing a standardized set of assessment and scoring procedures according to the latest guidelines and gold-standard techniques and measures that can be used reliably at different laboratories. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Postural control assessment Basic Protocol 2: Balance assessment Basic Protocol 3: Sleep architecture assessment Basic Protocol 4: Salivary cortisol analysis.

Social jetlag affects jump skills in sub-elite volleyball players

Social jetlag (SJL), resulting from misalignment between biological rhythms and social schedules, has emerged as a prevalent phenomenon in modern society, particularly among young athletes. However, the effect of SJL on performance is poorly studied. Jump and dynamic balance are two key skills in volleyball, as the first allows the player to perform better both during the offense and defense phase, and the second is fundamental in landing and in injury prevention. Therefore, our aim was to investigate the effect of SJL on jump skill performance and balance in female volleyball players. Thirty female volleyball players (mean age: 17.3 ± 0.88 years) participated in the study. SJL was assessed using the Munich ChronoType Questionnaire (MCTQ), integrated with Jankowsky's sleep-corrected formula. Jump skill performance was evaluated using a standardized jump test, the Vertec Jump Test, while balance was assessed with the Y Balance Test. The tests were performed at 09:00 a.m. and at 06:00 p.m. The results revealed that players with greater SJL exhibited decreased jump performance, characterized by lower vertical jump height (p = 0.02). Furthermore, players with lower SJL showed the typical difference between morning and afternoon performance (p = 0.001), demonstrating their synchronization between biological rhythms and social commitments, while no statistically significant difference between the two sessions was shown in players with higher SJL. Regarding balance, no significant association with SJL was found, but the morning session yielded lower results than the afternoon one (p = 0.01). These findings highlight the detrimental impact of SJL on jump skill performance, underscoring the importance of optimizing sleep-wake schedules and circadian alignment to enhance athletic performance. Future research should explore targeted interventions, such as sleep hygiene education, to minimize social jetlag and promote optimal performance in adolescent athletes.

Interactions between sleep-wake cycle on balance control of elderly people

Analysis of sleep-wake cycle in elderly people plays an important role in the quality of life of this population. The goal of this study is to analyze circadian rhythm of elderly people with actigraphy, subjective questionnaires and their relationship with balance control evaluated by center of pressure (COP) variables. The sleep-wake cycle of nine elderly subjects were evaluated using a wearable actigraph for 14 days. Questionnaires which evaluates chronotype, sleep quality and daytime sleepiness were administered and their balance control during quiet standing position was assessed by portable force platform. Measures of active phase amplitude (M10), rest amplitude (L5) total sleep time (TST) and time in bed (TIB) from actigraphy data and questionnaires results were correlated with COP variables. The actigraphy parameter that shows larger nocturnal activities (L5) showed positive correlations with larger COP excursions, whereas variability of M10, which can be interpreted as smaller routines of daily activities, showed negative correlations. Besides, TST and TIB showed positive correlations with COP variables.

The Effect of a Cognitive Dual Task on Gait Parameters among Healthy Young Adults with Good and Poor Sleep Quality: A Cross-Sectional Analysis

Background: Sleep quality is known to affect automatic and executive brain functions such as gait control and cognitive processing. This study aimed to investigate the effect of dual tasks on gait spatiotemporal parameters among young adults with good and poor sleep quality. Methods: In total, 65 young adults with a mean age of 21.1 ± 2.5 were assessed for gait analysis during single-task and dual-task conditions. The participants' sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) and gait was assessed using the BTS Gaitlab System. The participants were asked to walk at natural speed as a single-task condition, followed by walking while performing a cognitive task as a dual-task condition. The parameters assessed included the gait velocity (m/s), cadence (steps/min), step width (m), and stride length (m). The dual-task cost (DTC) on each gait parameter was calculated. The Mann-Whitney U test was used to compare the differences in the DTC on gait variables between the good and poor sleep quality groups and the Spearman correlation test was used to assess the correlation between total PSQI scores and the DTC. Results: At a significance level of p < 0.05, a significant difference in cadence between the two sleep quality groups was observed, in addition to a positive correlation between sleep quality and the DTC effect on gait mean velocity, cadence, and stride length. Our findings also revealed a greater DTC in participants with poorer sleep quality. Conclusions: These findings contribute to our perception of the significance of sleep quality in gait performance while multitasking in younger populations.

Sleep quality and its association with anxiety, stress, sleep-related beliefs and attitudes and postural control in young adults: a cross-sectional study

OBJECTIVES

Adequate sleep is essential for young adults, as this age group primarily consists of students, job seekers, and working people constantly managing a hectic lifestyle. Poor quality of sleep, which is essential for physical and mental well-being in the short and long term, can result in impaired overall health. However, there exists a gap in the literature regarding the factors affecting sleep among young adults. Hence, the objective of this study was to find the prevalence of sleep-related parameters (sleep health, hygiene, and sleep-related beliefs and attitudes) and potential risk factors for sleep quality and to investigate the association between sleep and postural control in young adults.

METHODS

This prospective, cross-sectional, analytical study included 181 young adults, 113 (62.43 %) females, and 68 (37.57 %) males, with a mean age of 23.82 ± 2.88 years. Sleep quality, health, beliefs, hygiene, stress, anxiety, and depression were assessed using questionnaires. Postural control was assessed using center of pressure (COP) indices.

RESULTS

The overall prevalence of poor sleep quality was 79.01 % among young adults. Multiple linear regression showed that predictors explained 44 % of sleep quality variance (adjusted R square=0.44, f (12,168) = 20.91, p<0.05). Poor sleep-related beliefs and attitudes (95 % CI [0.037, 0.679], p=0.029), higher perceived stress (95 % CI [0.005, 0.219], p=0.039), higher anxiety severity (95 % CI [0.108, 0.526], p=0.003), and poor COP stability index A/P (95 % CI [4.986, 11.248], p=0.00) were found to be significant predictors of poor sleep quality.

CONCLUSIONS

High anxiety and stress, and poor dysfunctional beliefs and attitudes about sleep are predictors of poor sleep quality in young adults. These factors may significantly affect sleep quality and the experience of restful sleep among young adults. Also, poor sleep quality is associated with reduced postural control (decreased stability in the A/P direction). These findings are crucial for improving young adults' overall health and well-being, as poor sleep is highly prevalent among this age group.

Association between Self-reported Sleep Quality and Single-task Gait in Young Adults: A Study Using Machine Learning

Objective  The objective of the present study was to find biomechanical correlates of single-task gait and self-reported sleep quality in a healthy, young population by replicating a recently published study. Materials and Methods  Young adults ( n  = 123) were recruited and were asked to complete the Pittsburgh Sleep Quality Inventory to assess sleep quality. Gait variables ( n  = 53) were recorded using a wearable inertial measurement sensor system on an indoor track. The data were split into training and test sets and then different machine learning models were applied. A post-hoc analysis of covariance (ANCOVA) was used to find statistically significant differences in gait variables between good and poor sleepers. Results  AdaBoost models reported the highest correlation coefficient (0.77), with Support-Vector classifiers reporting the highest accuracy (62%). The most important features associated with poor sleep quality related to pelvic tilt and gait initiation. This indicates that overall poor sleepers have decreased pelvic tilt angle changes, specifically when initiating gait coming out of turns (first step pelvic tilt angle) and demonstrate difficulty maintaining gait speed. Discussion  The results of the present study indicate that when using traditional gait variables, single-task gait has poor accuracy prediction for subjective sleep quality in young adults. Although the associations in the study are not as strong as those previously reported, they do provide insight into how gait varies in individuals who report poor sleep hygiene. Future studies should use larger samples to determine whether single task-gait may help predict objective measures of sleep quality especially in a repeated measures or longitudinal or intervention framework.

The interplay between cognition, functional and dual-task gait in persons with a vestibular disorder versus healthy controls

Close links exist between vestibular function and cognition. Dual-task (DT) tests may have ecological validity to assess the impact of daily life cognitive-motor demands in people with vestibular dysfunction (PwVD), functional gait and falls risk. The present paper aimed at building predictive models for functional gait under DT conditions, while clarifying the impact of vestibular dysfunction, individual characteristics, varying task types and motor-cognitive demands. Case-controlled observational study with 39 PwVD and 62 healthy participants. The Functional Gait Assessment (FGA), with and without an additional motor, numeracy, or literacy task, was completed. Multiple linear regression was used to fit models to predict FGA under single and DT performance. Dual task cost (DTC, %) was calculated to assess DT interference on FGA performance using the equation: 100*(single task score-dual task score)/single-task score. Following Bonferroni corrections for multiple comparisons (corrected alpha level of 0.003), PwVD had poorer performance than controls for all FGA conditions (p < 0.001), motor (- 3.94%; p = 0.002) and numeracy (- 22.77%; p = 0.001) DTCs and spatial working memory (p = 0.002). The literacy DTC was marginally significant (- 19.39% p = 0.005). FGA single and DT motor, numeracy, and literacy models explained 76%, 76%, 66% and 67% of the variance respectively for PwVD. Sustained attention, visual memory and sex contributed to all models; short-term visual recognition memory, balance confidence, and migraine contributed to some models. Cognitive performance is impaired in PwVD. Motor, numeracy and literacy tasks impair functional gait performance. Cognitive assessment and FGA with a numeracy or literacy cognitive component should be included within assessment protocols and considered in the provision of targeted interventions for PwVD.

Association between Objective and Subjective Sleep Parameters with Postural Control Responses among Brazilian Schoolteachers

Objective  To investigate the impact of sleep quality on postural control in teachers. Methods  Cross-sectional study with 41 schoolteachers (mean age 45.7 ± 10.4 years). Sleep quality was assessed in two ways: objectively (through actigraphy), and subjectively (through the Pittsburgh Sleep Quality Index). Postural control was assessed in an upright posture during 3 trials of 30s (bipedal and semitandem stances in rigid and foam surfaces with eyes open) with a period of rest across trials, on a force platform, based in the center of pressure measurements in the anteroposterior and mediolateral directions. Results  The prevalence of poor sleep quality in this study sample was 53.7% ( n  = 22). No differences were found between Poor and Good sleep in the posturographic parameters (p > 0.05). Although, there was moderate correlation between postural control in the semitandem stance and subjective sleep efficiency for center of pressure area (rs = -0.424; p  = 0.006) and amplitude in anteroposterior direction (rs = -0.386; p  = 0.013). Discussion  There is correlation between poor sleep quality and postural control in schoolteachers, as sleep efficiency decreases, postural sway increases. Poor sleep quality and postural control were investigated in other populations, but not in teachers. Several factors such as work overload, insufficient time for physical activities, among others, can contribute to a worse perception of sleep quality, as well as deterioration in postural control. Further studies with larger populations are needed to confirm these findings.

Association of emotional and behavioral problems with sleep disturbance among Chinese adolescents: The moderation effect of academic performance

BACKGROUND

This study aimed to explore the association of emotional and behavioral problems with sleep disturbance among Chinese adolescents, and to test whether these associations vary with adolescents' academic performance.

METHODS

Data were from the 2021 School-based Chinese Adolescents Health Survey using a multistage, stratified-cluster, and random-sampling method to collect information from 22,684 middle school students in Guangdong Province, China.

RESULTS

Emotional problems (aOR = 1.34, 95 % CI = 1.32-1.36), conduct problems (aOR = 1.19, 95 % CI = 1.16-1.21), hyperactivity (aOR = 1.35, 95 % CI = 1.33-1.37), and peer problems (aOR = 1.06, 95 % CI = 1.04-1.09) were significantly associated with the increased risk of sleep disturbance among middle school students in Guangdong Province. The prevalence of sleep disturbance among adolescents was 29.4 %. There were significant interactions of emotional problems/conduct problems/peer problems/prosocial behavior with academic performance on sleep disturbance. Further stratification analyses by academic performance showed that adolescents with self-reported good academic performance had a higher risk of sleep disturbance than those students with self-reported average or poor academic performance.

LIMITATIONS

This study only included school students and used the cross-sectional design to preclude causality determination.

CONCLUSIONS

Our findings suggest that emotional and behavioral problems elevate the risk of sleep disturbance in adolescents. Adolescent academic performance plays a modulating role in these above-mentioned significant associations for sleep disturbance.

Detrimental effects of sleep deprivation on the regulatory mechanisms of postural balance: a comprehensive review

This review addresses the effects of sleep deprivation on postural balance based on a comprehensive search of articles dealing with this relationship in the electronic databases PubMed, Google Scholar, and ScienceDirect. Evidence suggests that postural balance is sensitive to acute and chronic sleep deprivation for everyone, including young and healthy subjects. Pathologies, aging and the circadian pattern aggravate and/or accentuate the effects of sleep deprivation on postural balance. It turns out that the different systems of information taking, decision making, and motor execution of the postural balance function are negatively affected by sleep deprivation. For example, regarding the information taking system, the sensitivity of visual perception and visuo-spatial performance and the oculomotricity are disrupted and the vestibulo-ocular reflex and the sensory reweighting are altered. Regarding the decision making system, the different brain areas activated for the regulation of postural balance are less active after sleep deprivation and the executive function and perception of verticality are impaired. Regarding the motor execution system, the agonist-antagonist muscle coordination can be modified. However, the different detrimental effects induced for each system of the postural balance function are not yet fully known and deserve further exploration in order to better understand them.

Relationship between physical activity level and sleep quality with postural control and hemodynamic response in the prefrontal cortex during dual-task performance

Understanding the cortical activation and postural control behavior during dual-task (DT) has been an object of study. However, despite the multiple benefits of exercise and good sleep quality, less is known about the correlation between physical activity (PA) and sleep quality (SQ) on postural control and brain activation under dual-task performance. This study aimed to analyze the correlation between PA level and SQ with postural control performance and hemodynamic response in the prefrontal cortex during the DT performance in young adults. Thirty-four healthy young adults (mean age ± SD = 22.91 ± 3.90 years) participated in this study, and they performed a single-task and cognitive and motor DT using their smartphones. Postural control was assessed using a force plate to record the center of pressure (CoP) data (total excursion of CoP (TOTEX CoP), displacements of the CoP in anterior-posterior (CoP-AP) and medial-lateral (CoP-ML) directions, mean total velocity displacement of CoP (MVELO CoP), mean displacement velocity of CoP in anterior-posterior (MVELO CoP-AP) and medial-lateral (MVELO CoP-ML) directions, amplitude of CoP in anterior-posterior (A-AP) and medial-lateral (A-ML) directions, and 95% confidence ellipse sway area (CEA)). The hemodynamic response was measured by the oxyhemoglobin and deoxyhemoglobin concentrations using the functional near-infrared spectroscopy. The Pittsburg Sleep Quality Index and International Physical Activity Questionnaire-Short Form questionnaires assessed SQ and level of PA, respectively. Results indicated a positive correlation between SQ and cognitive DT cost for CoP-ML (r_s = 0.422, p = 0.013), MVELO CoP-ML (r_s = 0.422, p = 0.013) and A-ML (r_s = 0.579, p < 0.001). There were no significant relations between the other outcomes (p > 0.05). In conclusion, poor sleep quality was associated with a worse postural control performance in CoP-ML, MVELO CoP-ML and A-ML parameters under cognitive dual-task conditions. The differences found in the postural control and hemodynamic response during dual-task performance do not correlate with physical activity level.

Postural sway does not differentiate individuals with chronic low back pain, single and multisite chronic musculoskeletal pain, or pain-free controls: a cross-sectional study of 229 subjects

BACKGROUND CONTEXT

Physical activity in its various forms are the most recommended prevention and treatment strategy for chronic low back pain (CLBP). Standing postural stability is a prerequisite for many types of physical activities. Systematic reviews have investigated the evidence for an association between CLBP and postural stability but results remain inconclusive.

PURPOSE

Our primary objective was to compare postural stability between pain-free controls and subjects with CLBP with or without leg pain and single and multisite chronic musculoskeletal pain subjects. The secondary objectives were to evaluate the association between postural stability with CLBP intensity and duration, demographics, physical characteristics and validated health and pain-related patient-reported outcome measures (PROMs).

STUDY DESIGN/SETTING

Cross-sectional study in a private chiropractic clinic setting PATIENT SAMPLE: Subjects included 42 pain-free controls and 187 patients with chronic musculoskeletal pain divided into CLBP with or without leg pain and single and multisite pain groups.

OUTCOME MEASURES

Pain intensity was measured using the numerical pain rating scale, PROMs Central Sensitization Inventory, Tampa Scale of Kinesiophobia, The Depression Scale, EuroQol-5D, Roland-Morris Disability Questionnaire, and Pain and Sleep Questionnaire Three-Item Index disability. Group differences were measured using area and velocity of sway on the force plate.

METHODS

Postural stability was assessed using a force plate on four 60-second bipedal quiet stance tests: eyes open on a stable surface, eyes closed on a stable surface, eyes open on an unstable foam surface, eyes closed on an unstable foam surface. Following the clinic visit, subjects completed an online web-based data entry detailing pain history, demographic data, physical characteristics, pain intensity via the numerical pain rating scale, and PROMS.

RESULTS

Postural sway parameters did not differ between pain-free controls and subjects with CLBP with or without leg pain and single and multisite chronic musculoskeletal pain subjects. Furthermore, severity and duration of CLBP pain in addition to central sensitization, kinesiophobia, depression, quality of life, disability, and effect of pain on sleep only had very weak associations with postural stability.

CONCLUSIONS

Chronic musculoskeletal pain appears not to influence bipedal postural stability.

Investigations Concerning the Influence of Sleep Disorders on Postural Stability in Young Men

Lack of sleep is a factor that disrupts the receptors’ reception of information from the environment and contributes to the emergence of problems with maintaining balance. The main aim of the study was to determine whether sleep disorders affect postural stability in young men. The study participants were 76 male students who were divided into groups with good and poor sleep quality. The division was made based on the results obtained from the questionnaire of the Pittsburgh Sleep Quality Index (PSQI). In each group, postural stability had been tested using three main tests: Sensory Organization Test (SOT); Motor Control Test (MCT); and Adaptation Test (ADT). The results of the analysis show that the obtained results differ in the examined groups under the SOT test. Different values of the tested parameters were noted among people with poor sleep quality and compared with the values of those who sleep well, which translates into a difference in the ability to maintain balance. The greatest impact is observed when using visual and a vestibular system to maintain a stable posture. It was confirmed that the lack of sleep significantly disturbs postural stability.

Circadian parameter as a possible indicator of gait performance and daily activity levels in chronic stroke survivors

Stroke recovery is a critical public health problem. It involves cognitive and physical impairments leading to physical inactivity. In addition, there are also sleep problems and disruption of the circadian rhythm. In this paper, we analyze the relation between cognitive impairments level, walking performance, sleep and circadian parameters of a group of chronic stroke survivors. Five stroke survivors enrolled in the study. The clinical assessments were: cognitive function (MoCA), the 10 meter-walking test (10MWT), and the 6 minutes walking test (6MWT). The circadian rhythm parameters were obtained for at least one week wearing the actimeters. There was a positive correlation between the duration of the main sleep episode and the MoCA scores. There were significant correlations between the 10MWT and 6MWT and the circadian parameters that were positive for most active period (M10), Interdaily stability (IS), Mesor and Amplitude and negative for intradaily variability (IV). Our results indicate that gait speed and resistance are correlated to circadian rhythm synchronization, lower rhythm variability and more defined activity-rest episodes. This preliminary study underscores the importance of including a continuous measure of sleep and activity cycles in the assessment of stroke survivors.

Changes in static balance during pregnancy and postpartum: A systematic review

BACKGROUND

Because pregnant women show a high risk of falling, some researchers examined their balance during static standing. This systematic review summarized the findings from all studies evaluating static balance in women during pregnancy and postpartum.

RESEARCH QUESTION

Do pregnant and postpartum women show differences in static balance compared to non-pregnant women, and does static balance change during pregnancy and postpartum?

METHODS

Pubmed, Embase, CINAHL, and Web of Science databases were searched systematically from inception until Feb 23, 2022. Studies were eligible for inclusion if they measured COP sway with a force plate during bipedal static standing, and compared COP outcomes between healthy pregnant or postpartum women and non-pregnant women, and/or during different stages of pregnancy and the postpartum period. Methodological quality was assessed overall with a modified version of the Downs and Black checklist, and specifically related to COP measurement by using recommendations of Ruhe et al. (2010). The protocol was registered in PROSPERO (CRD42020166302).

RESULTS

Thirteen studies were included. Because methodological approaches varied greatly between studies, results were summarized descriptively. Studies reported either greater overall and anteroposterior COP sway magnitude, velocity and variability in women from the second half of pregnancy until six months postpartum compared to non-pregnant controls, or no differences in static balance. Changes in static balance throughout pregnancy were generally not found. Finally, there was no clear consensus on the influence of pregnancy on the reliance on visual inputs for balance control, and on whether differences in balance in pregnant and postpartum women reflect poorer balance or positive adaptations to the physical changes experienced during pregnancy.

SIGNIFICANCE

Methodological heterogeneity between studies prevented us from drawing strong conclusions regarding the effect of pregnancy on static balance. Assessing the methodological quality of the studies revealed weaknesses that should be taken into account in future studies.

Association Between Sleep Parameters and Postural Control: A Literature Review

Background and Objective The purpose of the review was to explore the association between sleep parameters and postural control.Methods The PubMed, Science Direct, and EBSCO were searched using the keywords ‘sleep’ including either sleep quality, sleep deprivation, poor sleep quality; and ‘postural control’ including either dynamic balance, static balance, postural balance, and balance control. Related studies published till December 2017 were selected.Results Acute sleep deprivation resulted in an impairment in postural control. Chronic sleep deprivation and postural control were also found to be related in a similar way to that of total sleep deprivation, thus affecting postural control negatively. Time of day was found to influence the postural control such that the postural control was better in the morning than in the latter part of the day. A study of the impact of aging on the effects of sleep deprivation on postural control revealed that loss of sleep had a more disturbing effect on postural control in the olderadult group than in younger participants, thus indicating a high risk of fall among the elderly.Conclusions Despite various limitations and methodological differences, this review has identified a negative influence on postural control due to impaired sleep in a wide range of populations, indicating the need for a more focused approach to sleep when assessing and measuring postural control.

Is Balance Control Affected by Sleep Deprivation? A Systematic Review of the Impact of Sleep on the Control of Balance

Background

Sleep is a complex physiological function that should be addressed from different perspectives and consider the circadian rhythm. Sleep deprivation, either acute or chronic, negatively affects several functions, including motor control. Balance control is essential in several daily life activities and balance problems are related to falls.

Research Question

This review focuses on how sleep conditions impact balance control.

Methods

Systematic literature review according to PRISMA guidelines.

Results

The literature provided strong evidence that acute sleep deprivation impairs postural control. Chronic sleep deprivation as well as low sleep quality had similar effects, although there is a lower number of works addressing this issue. Furthermore, time awake worsens postural controls and it can be used to detect sleepiness and fatigue. The sleep deprivation showed a stronger negative effect on postural control when removing the visual information (eyes closed) than when reducing proprioceptive feedback (soft surface). There is scarce literature about the effects of chronotype, circadian patterns and chronic sleep deprivation, a frequent problem, on balance control; however they consistently indicate that there is an relationship between them. Most of the studies only consider one-night (acute) sleep deprivation without monitoring prior sleep conditions and the circadian rhythm phase of the participants. However, a few studies indicated that these factors must be considered.

Significance

These results suggest that the sleep conditions of a subject should be considered for several days prior to balance control tests. Therefore, we propose a revision of current postural measurement protocols to include sleep assessment, such as sleep quality questionnaires or actimetry, and to consider the circadian rhythm of the participants to plan the hour of the tests.

Static postural stability and neuropsychological performance after awakening from REM and NREM sleep in patients with chronic insomnia: a randomized, crossover, overnight polysomnography study

STUDY OBJECTIVES

Chronic insomnia disorder (CID) is a common sleep disorder, with a prevalence ranging from 6% to 10% worldwide. Individuals with CID experience more fragmented sleep than healthy controls do. They awaken frequently during the night and have a higher risk of injury from falling. Awakening from different sleep stages may have different effects on postural stability and waking performance. However, limited research has been conducted on this topic.

METHODS

This prospective randomized crossover study was conducted between January 2015 and January 2017. We included 20 adults aged 20-65 years who fulfilled diagnosis criteria for CID. Participants underwent two overnight polysomnography studies with an interval of at least 7 days. They were awakened during either rapid eye movement (REM) sleep or N1/N2 sleep alternatively. We compared measurements of static postural stability, vigilance scores, and neuropsychological tests between REM and N1/N2 sleep awakening.

RESULTS

Polysomnography parameters between the two nights were comparable. Participants who were awakened from REM sleep had worse static postural stability than those with N1/N2 awakening. Compared with N1/N2 awakening, larger mean sway areas of center of pressure (COP; p = 0.0413) and longer COP mean distances (p = 0.0139) were found in REM sleep awakening. There were no statistically significant differences in vigilance scores or neuropsychological tests between the two nights.

CONCLUSIONS

REM sleep awakening was associated with worse static postural stability than was N1/N2 awakening. No statistically significant differences were found in waking performance in alertness or in neuropsychological tests between N1/N2 and REM sleep awakening.

Effect of Obstructive Sleep Apnea on the Risk of Injuries-A Nationwide Population-Based Cohort Study

Obstructive sleep apnea (OSA) has been reported to increase the risk of motor vehicle accidents. However, only few studies have investigated the effects of OSA on overall risk injury. The aim of study is to investigate whether OSA increases the risk of overall injury. The data were collected during 2000–2015 from Taiwan’s National Health Insurance Research Database. A total of 8901 individuals diagnosed with OSA were inpatients, or outpatients at least three times were enrolled. Finally, 6915 participants with OSA were included as the study cohort. We matched the study cohort with a comparison cohort, at a ratio of 1:4. Cox proportional hazards regression was used to analyse the association between OSA and overall injury. Patients with OSA had 83.1% increased risk of overall injury, compared to non-OSA individuals [adjusted hazards ratio (HR) = 1.831, confidence interval (CI) = 1.674–2.020, p < 0.001]. In the stratified age group, patients aged ≧65 years had the highest risk of injury (adjusted HR= 2.014; CI = 1.842–2.222, p < 0.001). Patients with OSA were at a higher risk of falls, traffic injury, poisoning, suffocation, suicide, and abuse or homicide than non-OSA individuals, with falls and traffic injury as the leading causes of injuries. The data demonstrated that patients with OSA have a higher risk of overall injury. The study results can be a reference for developing injury prevention strategies in the future. The general population and clinicians should have more awareness regarding OSA and its negative effects on injury development.

Sleep deprivation affects gait control

Different levels of sleep restriction affect human performance in multiple aspects. However, it is unclear how sleep deprivation affects gait control. We applied a paced gait paradigm that included subliminal rhythm changes to analyze the effects of different sleep restriction levels (acute, chronic and control) on performance. Acute sleep deprivation (one night) group exhibited impaired performance in the sensorimotor synchronization gait protocol, such as a decrease in the Period Error between the footfalls and the auditory stimulus as well as missing more frequently the auditory cues. The group with chronic sleep restriction also underperformed when compared to the control group with a tendency to a late footfall with respect to the RAC sound. Our results suggest that partial or total sleep deprivation leads to a decrease in the performance in the sensorimotor control of gait. The superior performance of the chronic sleep group when compared to the acute group suggests that there is a compensatory mechanism that helps to improve motor performance.

Cross-Cultural Adaptation, Reliability, and Psychophysical Validation of the Pain and Sleep Questionnaire Three-Item Index in Finnish

Reciprocal relationships between chronic musculoskeletal pain and various sleep disturbances are well established. The Pain and Sleep Questionnaire three-item index (PSQ-3) is a concise, valid, and reliable patient-reported outcome measure (PROM) that directly evaluates how sleep is affected by chronic low back pain (CLBP). Translation and cross-cultural validation of The Pain and Sleep Questionnaire three-item index Finnish version (PSQ-3-FI) were conducted according to established guidelines. The validation sample was 229 subjects, including 42 pain-free controls and 187 subjects with chronic musculoskeletal pain. Our aims were to evaluate internal consistency, test-retest reliability, measurement error, structural validity, convergent validity, and discriminative validity and, furthermore, to study the relationships between dizziness, postural control on a force plate, and objective sleep quality metrics and total PSQ-3-FI score. The PSQ-3-FI demonstrated good internal consistency, excellent test-retest reliability, and small measurement error. Confirmatory factor analysis confirmed acceptable fit indices to a one-factor model. Convergent validity indicated fair to good correlation with pain history and well-established pain-related PROMs. The PSQ-3-FI total score successfully distinguished between the groups with no pain, single-site pain, and multisite pain. A higher prevalence of dizziness, more impaired postural control, and a general trend towards poorer sleep quality were observed among subjects with higher PSQ-3-FI scores. Postural control instability was more evident in eyes-open tests. The Finnish PSQ-3 translation was successfully cross-culturally adapted and validated. The PSQ-3-FI appears to be a valid and reliable PROM for the Finnish-speaking CLBP population. More widespread implementation of PSQ-3 would lead to better understanding of the direct effects of pain on sleep.

Postural Control and Sleep Quality in Cognitive Dual Tasking in Healthy Young Adults

Although sleep quality disorders can have a negative effect on postural control, studies about this subject are scarce. The aim of this study is to assess the differences in standing posture performance during dual tasking between healthy young adults with a good and poor sleep quality. Thirty-five healthy participants (23.09 ± 3.97 years) performed a postural task (standing posture single task ((ST)) and a dual task (DT): quiet standing while performing a concurrent cognitive task, while the total excursion of the center of pressure (TOTEX CoP), the displacement anterior–posterior (CoP-AP) and medial–lateral (CoP-ML), the mean total velocity displacement of CoP (MVELO CoP) and ellipse sway area (CEA) were measured with a force plate. After assessing the sleep quality with the Pittsburgh Sleep Quality Index, they were divided into two groups (good ((n = 21)) and poor ((n = 14)) sleep quality) to establish comparisons. This study revealed no significant differences in TOTEX CoP, CoP-ML, CoP-AP, MVELO CoP, and CEA among both sleep quality groups. In conclusion, differences in the sleep quality (good or poor sleep quality) among young adults appear not to be a relevant factor in the CoP variation, but the DT versus ST can compromise postural control performance independently of the sleep quality.

State and Trait Fatigue and Energy Predictors of Postural Control and Gait

Compromised attentional resources during perceived fatigue has been suggested to alter motor control. The authors determined if measures of postural control and gait are predicted by state and trait physical and mental fatigue and energy, and how these relationships are modified by sex, sleep quality, and physical activity. Young adults (n = 119) completed the Modified Clinical Test of Sensory Integration, overground walking, and questionnaires to quantify fatigue and energy, sleep quality, and physical activity. Regression models indicated that trait fatigue, trait energy, and sleep quality were predictors of postural control (p ≤ .02, R2 ≥ .04). State fatigue, state energy, and sex were predictors of gait (p ≤ .05, R2 ≥ .03). While the variance explained was low (3-13%), the results demonstrate perceptions of fatigue and energy may influence posture and gait.

Associations between longitudinal trajectories of insomnia symptoms and sleep duration with objective physical function in postmenopausal women: the Study of Women's Health Across the Nation

STUDY OBJECTIVES

Examine the association between trajectories of self-reported insomnia symptoms and sleep duration over 13 years with objective physical function.

METHODS

We utilized data from 1627 Study of Women's Health Across the Nation (SWAN) participants, aged 61.9±2.7 y at the end of the 13-y follow-up. Latent class growth models identified trajectories of insomnia symptoms (trouble falling asleep, frequent night-time awakenings, and/or early-morning awakening) and sleep duration over 13 y. Physical function tests were performed at the end of the 13-y period: 40-ft walk, 4-m walk, repeated chair stand, grip strength, and balance. Multivariable regression analyses examined each physical function measure according to the insomnia symptom or sleep duration trajectory group.

RESULTS

Five insomnia symptom trajectories and two sleep duration trajectories were identified. Women with a consistently high likelihood of insomnia symptoms and women with a decreased likelihood of insomnia symptoms (i.e., improving) had slower gait speed (3.5% slower 40-ft walk [consistently high], 3.7% slower 4-m walk [improving]; each P≤.05) than those with a consistently low likelihood of insomnia symptoms. In contrast, women with a steep increase in the likelihood of insomnia symptoms over time and women with persistent insufficient sleep duration had lower odds of having a balance problem (odds ratio [OR]=0.36 and OR=0.61, respectively; each P<.02) compared to those with a consistently low likelihood of insomnia symptoms and those with persistent sufficient sleep duration, respectively.

CONCLUSION

These results suggest that women's sleep during midlife has important implications for maintaining physical function during the transition into older adulthood.

Postural stability and fall risk in patients with obstructive sleep apnea: a cross-sectional study

PURPOSE

Nocturnal hypoxia and daytime sleepiness resulting from fragmented sleep may impair the ability of postural stability in subjects with OSA. This study investigates the effect of disease severity on postural stability and whether or not it poses a fall risk in individuals with obstructive sleep apnea (OSA).

METHODS

Forty-nine patients with OSA diagnosed by all-night polysomnography (apnea-hypopnea index (AHI) ≥ 5) and aged 51.4 ± 7.2 years were included in the study. The patients were divided into two groups as severe OSA (AHI ≥ 30, n = 24) and non-severe OSA (5 ≤ AHI ≤ 30, n = 25). All patients were subjected to testing for postural stability (PS), limits of stability (LOST), and the stability index for fall risk (fall risk SI) with the Biodex Balance System®. Daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS). Biodex measurements and daytime sleepiness were compared between severe and non-severe OSA groups. Univariate analysis was conducted to explore if AHI, ESS score, lowest SaO₂ (%), sleep stages (%), or total arousal index predict postural stability scores.

RESULTS

Overall and anterior-posterior PS indices were higher in the severe OSA group (p < 0.05). Dynamic PS and fall risk indices did not differ between groups. AHI and lowest SaO₂ (%) were found to be an independent predictor for both overall PS (r = 0.300 and r = 0.286, respectively) and fall risk SI (r = 0.296 and r = 0.374, respectively), whereas stage N1 (%) and stage N3 (%) were an independent predictor for overall LOST score (r = -0.328 and r = 0.298, respectively) (p < 0.05).

CONCLUSION

Static postural stability of individuals with severe OSA is worse than those with non-severe OSA. Static postural stability worsens, and fall risk increases as AHI increases and the lowest SaO₂ decreases in individuals with OSA. On the other hand, dynamic postural stability worsens as stage N1 (%) sleep increases and stage N3 (%) sleep decreases. While nocturnal hypoxia indicators such as AHI and lowest SaO₂ are associated with static postural stability, sleep structure-related variables are associated with dynamic stability. Including postural stability assessments in the clinical practice for OSA may help addressing workplace accidents or tendency to fall.

TRIAL REGISTRATION

www.ClinicalTrials.gov registration number: NCT03589417.

Is poor sleep quality associated with a deterioration in postural control?

OBJECTIVE

The primary aim was to investigate whether any association exists between poor sleep quality and deterioration in postural control among university student population.

MATERIALS AND METHODS

A case-control study was conducted in which sleep quality of 119 university students from different departments of Jamia Millia Islamia University, New Delhi, India was assessed using Pittsburgh sleep quality index (PSQI) following which the participants postural control, or dynamic balance was measured using the Y balance test (YBT). The participants were divided into two groups (A and B) based on their PSQI cut off scores. The YBT data was then evaluated for the dynamic balance assessment of the participants.

RESULTS

The mean age of the participants was 22.23±2.29 out of which 86 were female and 33 were male. The mean BMI of the participants was 21.58±3.66. Group A included 63 participants who had "good" sleep quality (global PSQI score < 5) whereas group B included 56 participants who had "poor" sleep quality (global PSQI score ≥ 5). Group comparisons based on t-test revealed a significant difference (p<0.05) between means of the two groups, with the mean balance of group A being greater than that of group B. Also, chi-square testing showed no significant association between the BMI and dynamic balance scores for the participants (p<0.10).

CONCLUSION

The findings of the study conclude that poor sleep quality is associated with a deterioration of postural control in university students. The study also revealed that there was no association between BMI and dynamic balance in this population.

Evaluation of the postural balance and visual perception in young adults with acute sleep deprivation

BACKGROUND/OBJECTIVE

Few studies have suggested a relationship between vestibular system and sleep deprivation. The aim of the present study is to investigate the effects of acute sleep deprivation lasting 24 hours or more on the postural balance and the visual abilities related to the vestibular system in healthy young adults.

METHODS

Thirty-one healthy young adults (8 males, 23 female; ages 18- 36 years) who had experienced at least 24 hours of sleep deprivation were included in the study. Subjects made two visits to the test laboratory. One visit was scheduled during a sleep deprivation (SD) condition, and the other was scheduled during a daily life (DL) condition. Five tests- the Sensory Organization Test (SOT), Static Visual Acuity Test (SVA), Minimum Perception Time Test (mPT), Dynamic Visual Acuity Test (DVA), and Gaze Stabilization Test (GST)- were performed using a Computerized Dynamic Posturography System.

RESULTS

A statistically significant difference was found between SD and DL measurements in somatosensorial (p = 0.003), visual (p = 0.037), vestibular (p = 0.008) ratios, and composite scores (p = 0.001) in SOT. The mPT results showed a statistically significant difference between SD and DL conditions (p = 0.001). No significant difference was found between SD and DL conditions in the comparison of the mean SVA (p = 0.466), DVA (p = 0.192), and GST head velocity values (p = 0.160).

CONCLUSIONS

Sleep deprivation has a considerable impact on the vestibular system and visual perception time in young adults. Increased risk of accidents and performance loss after SD were thought to be due to the postural control and visual processing parameters rather than dynamic visual parameters of the vestibular system.

Does the poor sleep quality affect the physical activity level, postural stability, and isometric muscle strength in Saudi adolescents? A comparative study

OBJECTIVES

To  compare physical activity, postural stability, and muscle strength in Saudi adolescents with normal and poor sleep quality. Methods: This cross-sectional study investigated 62 Saudi adolescents between December 2017 and April 2018 at Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia. Participants were classified into 2 equal groups; one with normal sleep (NS) and the other with poor sleep (PS). TecnoBody balance system was used to measure postural stability, ActiGraph to assess physical activity, and hand dynamometer and pinch gauge to assess hand grip and key pinch strength respectively. Results: At low platform stability, PS group showed poorer postural stability indices than NS group either with eyes opened or closed (p less than 0.05). ActiGraph data revealed that the physical activity parameters including the total steps count, total activities count, activity rate, and the vigorous activity time were significantly lower in PS group (p less than 0.05). The PS group had significantly more total sedentary time than the NS group. Muscle strength parameters did not show any significant difference between groups (p greater than 0.05).  Conclusion: Poor sleep significantly impaired postural stability and physical activity in Saudi adolescents. However, poor sleep had no effect on their isometric muscle strength.

Assessment of postural control after sleep deprivation with a low-cost portable force plate

It is well-known that acute sleep deprivation affects negatively postural control. The analysis of sleep quality during long periods and its impact on motor control and learning performance are crucial aspects of human health. Nevertheless, there is conflicting evidence regarding which postural control variables are more prone to change due to sleep deprivation. Moreover, very few clinicians have at their disposal expensive force plates to measure such variables, so the use of a low-cost portable device could be very interesting. Therefore, we aimed to identify which posture control variables, obtained from a low-cost plate, are more sensitive to sleep deprivation. In order to do so, we have performed a set of experiments with volunteers before and after a night without sleep. Eight participants took part of the study and had their balance measured by a Wii Balance Board before and after one night of sleep deprivation. They were asked to keep a quiet stance on top of the plate with their eyes open and closed, in a balanced design. The main results showed that, regardless the visual information, sleep deprivation has deepest impact on the anterior-posterior center of pressure displacement. Sleep deprivation without visual information had a more pronounced (large effect size) impact on the mean sway in the anterior-posterior direction and its distribution variation. The information that sleep deprivation has a more meaningful impact on anterior-posterior center of pressure excursion may help clinicians and healthcare professionals to better deal with its implications.

Examining Relationships between Multiple Self-Reported Sleep Measures and Gait Domains in Cognitively Healthy Older Adults

BACKGROUND

Gait-related changes in older adulthood may be related to changes in cognition (e.g., executive functioning), and recent work suggests that different self-reported measures of sleep may be tied to contrasting aspects of executive functioning. However, the relationship between these self-reported sleep measures and gait domains has not been explored. Such an investigation would be useful in helping to determine which older adults might exhibit changes in gait as well as experience other gait-associated changes (e.g., increased fall risk).

OBJECTIVE

To examine associations between different aspects of self-reported sleep and gait domains in a sample of cognitively healthy older adults.

METHOD

A total of 423 older adults (mean age 69.9 years, range 50-92) completed self-report measures of sleep quality, daytime sleepiness, and sleep-related distress. The participants also completed an objective, electronic measure of both single-task and dual-task gait (i.e., GAITRite). Principal component analyses were used to elucidate the solution for each gait condition, and multiple linear regression was used to examine the contributions of sleep measures to variability in gait performance.

RESULTS

A 5-component solution of the single-task condition and a 4-component solution of the dual-task condition were identified. Multiple linear regressions revealed that a poorer sleep quality was associated with greater single-task and dual-task asymmetry. Greater daytime sleepiness was associated with increased dual-task gait variability and postural control. After controlling for the effects of other facets of sleep, sleep-related distress was not associated with any gait domain.

CONCLUSIONS

Among cognitively healthy older adults,sleep quality and daytime sleepiness, but not sleep-related distress, are associated with aspects of gait. Patients who report these symptoms should be assessed and monitored for possible changes in gait.

Insomnia and daytime sleepiness: risk factors for sports-related concussion

OBJECTIVE/BACKGROUND

Poor quality and inadequate sleep are associated with impaired cognitive, motor, and behavioral components of sport performance and increased injury risk. While prior work identifies sports-related concussions as predisposing factors for poor sleep, the role of sleep as a sports-related concussion risk factor is unknown. The purpose of this study was to quantify the effect of poor sleep quality and insomnia symptoms on future sports-related concussion risk.

PATIENTS/METHODS

In this study, 190 NCAA Division-1 athletes completed a survey battery, including the Insomnia Severity Index (ISI) and National Health and Nutrition Examination Survey (NHANES) Sleep module. Univariate risk ratios for future sports-related concussions were computed with ISI and NHANES sleepiness scores as independent predictors. An additional multiple logistic regression model including sport, sports-related concussion history, and significant univariate predictors jointly assessed the odds of sustaining a concussion.

RESULTS

Clinically moderate-to-severe insomnia severity (RR = 3.13, 95% CI: 1.320-7.424, p = 0.015) and excessive daytime sleepiness two or more times per month (RR = 2.856, 95% CI: 0.681-11.977, p = 0.037) increased concussion risk. These variables remained significant and comparable in magnitude in a multivariate model adjusted for sport participation.

CONCLUSION

Insomnia and daytime sleepiness are independently associated with increased sports-related concussion risk. More completely identifying bidirectional relationships between concussions and sleep requires further research. Clinicians and athletes should be cognizant of this relationship and take proactive measures - including assessing and treating sleep-disordered breathing, limiting insomnia risk factors, improving sleep hygiene, and developing daytime sleepiness management strategies - to reduce sports-related concussion risk and support overall athletic performance.

Day-to-day variations in sleep quality affect standing balance in healthy adults

Acute sleep deprivation is known to affect human balance and posture control. However, the effects of variations in sleep quality and pattern over consecutive days have received less attention. This study investigated the associations between day-to-day variations in sleep quality and standing balance in healthy subjects. Twenty volunteers (12 females and 8 males; age: 28.8 ± 5.7 years, body mass index: 23.4 ± 3.4 kg/m2, resting heart rate: 63.1 ± 8.7 bpm) with no history of sleep disorders or balance impairments participated in the study. Sleep and balance were assessed over two consecutive days. Sleep quality variations were assessed using sleep diary, actigraphy and heart rate variability (HRV) measures. Sleep was monitored at home, using an unobtrusive wearable device. Balance was assessed in a gait lab using foot centre of pressure (COP) displacement during quiet standing. Subjects with a day-to-day deterioration in sleep quantity and quality (i.e., decreased duration and increased fragmentation, increased nocturnal activity and decreased HRV) exhibited significant changes in balance (i.e., larger COP area, amplitude and standard deviation). Conversely, subjects with no significant alterations in sleep quantity and quality showed no significant changes in COP displacements. These results confirmed our hypothesis that changes in sleep quality and pattern over consecutive days may affect balance.

Potential for the development of light therapies in mild traumatic brain injury

Light affects almost all aspects of human physiological functioning, including circadian rhythms, sleep-wake regulation, alertness, cognition and mood. We review the existing relevant literature on the effects of various wavelengths of light on these major domains, particularly as they pertain to recovery from mild traumatic brain injuries. Evidence suggests that light, particularly in the blue wavelengths, has powerful alerting, cognitive and circadian phase shifting properties that could be useful for treatment. Other wavelengths, such as red and green may also have important effects that, if targeted appropriately, might also be useful for facilitating recovery. Despite the known effects of light, more research is needed. We recommend a personalized medicine approach to the use of light therapy as an adjunctive treatment for patients recovering from mild traumatic brain injury.

Sleep quality and its association with postural stability and fear of falling among Spanish postmenopausal women

OBJECTIVE

To analyze the association of sleep quality with postural balance, as measured with objective stabilometric parameters, and fear of falling (FoF), among Spanish postmenopausal women.

METHODS

In all, 250 women (60 ± 8 years) took part in this cross-sectional study. Sociodemographic and anthropometric data were collected, as well as information concerning history of falls and FoF. Anxiety and depression were assessed using the Hospital Anxiety and Depression Scale, and the Pittsburgh Sleep Quality Index was used to analyze sleep quality. Measurements of sway area (S), velocity (V), and mediolateral (RMSX) and anteroposterior (RMSY) displacements of the center of pressure were obtained with a resistive multisensor platform under both eyes-open (EO) and eyes-closed (EC) conditions to assess postural control. The independent associations of sleep quality with FoF and postural control were evaluated by multivariate linear and logistic regressions, respectively, adjusting for potential confounding variables.

RESULTS

SEO was independently associated (adjusted R = 0.073) with sleep duration (P < 0.001) and subjective sleep quality (P = 0.001), VEO (adjusted R = 0.156) with daytime dysfunction (P = 0.006) and sleep duration (P = 0.013), RMSXEO (adjusted R = 0.118) with subjective sleep quality (P = 0.005), and RMSYEO (adjusted R = 0.166) with sleep duration (P = 0.001) and daytime dysfunction (P = 0.046). Under EC condition, SEC (adjusted R = 0.014) was independently related with anxiety (P = 0.034), VEC (adjusted R = 0.148) with daytime dysfunction (P = 0.002) and sleep duration (P = 0.024), RMSXEC (adjusted R = 0.134) with subjective sleep quality (P < 0.001), and RMSYEC (adjusted R = 0.128) with sleep duration (P = 0.013) and daytime dysfunction (P = 0.033). Logistic regression showed that time since menopause (P = 0.003), body mass index (P = 0.001), and anxiety (P < 0.001), unlike sleep quality, were independently associated with FoF. The effect size of the model was medium (adjusted R= 0.162).

CONCLUSIONS

In Spanish postmenopausal women, sleep duration, subjective sleep quality, and daytime dysfunction were independent risk factors for worsened postural stability. FoF, anxiety, time since menopause onset, and body mass index, unlike sleep quality, were independently associated with poor postural stability.

Social jetlag impairs balance control

We assessed the impact of a common sleep disturbance, the social jetlag, on postural control during a period involving workdays and free days. The sleep habits of 30 healthy subjects were registered with a wrist actimeter for nine days (starting on Friday) and they participated in a set of four postural control tests carried out on Friday and on Monday. In addition, the subjects filled questionnaires about their sleep conditions and preferences. Actimetry measurements were used to calculate the Mid Sleep Phase (MSP). The difference between the MSP values on the workdays and free days measures the social jetlag. There were significant differences in sleep variables between workdays and free days. Postural control performance improved on Monday, after free sleep over the weekend, when compared with the tests performed on Friday. It seems that social jetlag affects brain areas involved in the control of posture, such as thalamus and the prefrontal cortex as well as the cerebellum, resulting in a worse performance in postural control. The performance improvement in the posture tests after the free days could be attributed to a lower sleep debt.

Alcohol-Induced Impairment of Balance is Antagonized by Energy Drinks

BACKGROUND

The acute administration of alcohol reliably impairs balance and motor coordination. While it is common for consumers to ingest alcohol with other stimulant drugs (e.g., caffeine, nicotine), little is known whether prototypical alcohol-induced balance impairments are altered by stimulant drugs. The purpose of this study was to examine whether the coadministration of a high-caffeine energy drink with alcohol can antagonize expected alcohol-induced increases in body sway.

METHODS

Sixteen social drinkers (of equal gender) participated in 4 separate double-blind dose administration sessions that involved consumption of alcohol and energy drinks, alone and in combination. Following dose administration, participants completed automated assessments of balance stability (both eyes open and eyes closed) measured using the Biosway Portable Balance System. Participants completed several subjective measures including self-reported ratings of sedation, stimulation, fatigue, and impairment. Blood pressure and pulse rate were recorded repeatedly.

RESULTS

The acute administration of alcohol increased body sway, and the coadministration of energy drinks antagonized this impairment. When participants closed their eyes, alcohol-induced body sway was similar whether or not energy drinks were ingested. While alcohol administration increased ratings of sedation and fatigue, energy drink administration increased ratings of stimulation and reduced ratings of fatigue. Modest increases in systolic and diastolic blood pressure following energy drink administration were also observed.

CONCLUSIONS

Visual assessment of balance impairment is frequently used to indicate that an individual has consumed too much alcohol (e.g., as part of police-standardized field sobriety testing or by a bartender assessing when someone should no longer be served more alcohol). The current findings suggest that energy drinks can antagonize alcohol-induced increases in body sway, indicating that future work is needed to determine whether this observation regarding neuromotor functioning applies to alcohol in combination with all types of stimulant drugs.

Biopsychosocial Measures Related to Chronic Low Back Pain Postural Control in Older Adults

This study examined the biopsychosocial measures related to postural control in the growing population of older adults (i.e., 60 years and older). The sample of the study consisted of 129 older adults (M = 74.45, SD = 6.95), with 34 males and 95 females; 36 were classified with chronic low-back pain (CLBP), and 93 without chronic low-back pain (NCLBP). Physical and psychosocial constructs were analyzed as predictors for postural control measures. Additionally, gender and classification of low-back pain were examined as moderators for all physical and psychosocial measures. Results demonstrated that physical and psychosocial measures were able to significantly predict composite, visual, and vestibular balance measures, but not somatosensory or preference balance measures. The chair-stand test, modified sit-and-reach test, sleep disturbance, and balance efficacy were all identified as individually significant predictors. Gender and CLBP did not moderate the utility of any predictor variables. Results of the current study re-confirm the importance of utilizing the biopsychosocial approach for future research examining postural control in older adults.