Principal component analysis detects sleepiness-related changes in balance 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.

Postural Stability Change Under Sleep Deprivation and Mental Fatigue Status

AbstractBACKGROUND: Based on posturography parameters during sleep deprivation (SD), a mental fatigue index (MFI) was constructed for healthy male cadets.METHODS: There were 37 young male subjects who volunteered for two successive days of SD. Their posturography balance, profile of mood status (POMS), and heart rate variability (HRV) were measured at four different times (10:00 and 22:00 of day 1, 10:00 and 22:00 of day 2). According to the methods used in our previous research, similar MFIs based on posturography parameters were computed. Then, correlations of MFIs with POMS scores and HRV values were evaluated by linear and nonlinear methods including quadratic, S-curve, growth, and exponential analyses.RESULTS: MFI continued to increase during SD and MFI as the independent variable had quadratic relationships with fluster (R² 0.057), depression (R² 0.067), and anger (R² 0.05) scores of POMS. A linear correlation was found between MFI and the depression score (R² 0.045) and MFI correlated linearly (R² 0.029) and nonlinearly (R² 0.03) with heart rate. Similarly, MFI reflected changes in the time and frequency domain parameters of HRV, with linear (R²range: 0.0290.082) or nonlinear (R²range: 0.0300.082) relationships.DISCUSSION: The increase of MFI was linked with amplification of personal negative moods and an imbalance of autonomic nervous system activity. The findings suggest that MFI might be a potential indicator of mental fatigue and provide a method to prevent driving fatigue and human errors.Cheng S, Yang J, Su M, Sun J, Xiong K, Ma J, Hu W. Postural stability change under sleep deprivation and mental fatigue status. Aerosp Med Hum Perform. 2021; 92(8):627632.

Differences in sensory reweighting due to loss of visual and proprioceptive cues in postural stability support among sleep-deprived cadet pilots

BACKGROUND

Sleep deprivation is known to diminish postural control.

RESEARCH QUESTION

We investigated whether sleep deprivation affects sensory reweighting for postural control due to loss of visual and proprioceptive cues.

METHODS

Two cohorts of cadet pilots were deprived of sleep for 40 h. Variabilty in force-platform center of pressure was analyzed based on the whole path length (WPL); circumference area (CA); mean of displacement along x and y axes and corresponding standard deviations (SDx, SDy); and frequency of body-sway intensity, all of which were recorded while the cadets stood with eyes open (NEO), eyes closed (NEC), and eyes closed on a foam platform base (FEC) A sleepiness index (SUBI) based on principal component analysis of selected Cohort 1 data (n = 37) was used to compare Cohort 2 data (n = 29) with scores for the Stanford Sleepiness Scale (SSS) and Pittsburg Sleep Quality Index (PSQI).

RESULTS

Balance began to deteriorate at 16 h for NEO and at 28 h for NEC and FEC (p < 0.05). At 40 h, WPL, CA, and SDy of COP for NEO indicated balance deteriorated further while WPL and SDy for NEC and WPL, CA, SDx, and SDy for FEC indicated balance incrementally improved. Frequency bias of body-sway differed between NEO, NEC, and FEC. In Cohort 2, the SUBI correlated significantly with SSS (p < 0.05), but not with PSQI.

SIGNIFICANCE

Effects of sleep deprivation were mitigated over time, suggesting that compensatory mechanisms influenced sensory reweighting for NEC and FEC between 28 and 40 h of sleep deprivation, but not for NEO. Frequency bias of body-sway suggested that sensory reweighting in the absence of visual cues differed from that in the absence of both visual and proprioceptive cues.

A feasibility study on age-related factors of wrist pulse using principal component analysis

Various analysis methods for examining wrist pulse characteristics are needed for accurate pulse diagnosis. In this feasibility study, principal component analysis (PCA) was performed to observe age-related factors of wrist pulse from various analysis parameters. Forty subjects in the age group of 20s and 40s were participated, and their wrist pulse signal and respiration signal were acquired with the pulse tonometric device. After pre-processing of the signals, twenty analysis parameters which have been regarded as values reflecting pulse characteristics were calculated and PCA was performed. As a results, we could reduce complex parameters to lower dimension and age-related factors of wrist pulse were observed by combining-new analysis parameter derived from PCA. These results demonstrate that PCA can be useful tool for analyzing wrist pulse signal.

Effects of Shift Work on the Postural and Psychomotor Performance of Night Workers

The purpose of the study was to investigate the effects of shift work on the psychomotor and postural performance of night workers. The study included 20 polysomnography technicians working schedule of 12-h night shift by 36-h off. On the first day of protocol, the body mass and height were measured, and an actigraph was placed on the wrist of each participant. On the second day of protocol, sleepiness by Karolinska Sleepiness Scale, postural control by force platform (30 seconds) and psychomotor performance by Psychomotor Vigilance Task (10 minutes) were measured before and after 12-h night work. Results showed that after 12-h night work, sleepiness increased by 59% (p<0.001), postural control variables increased by 9% (p = 0.048), and 14% (p = 0.006). Mean reaction time, and the number of lapses of attention increased by 13% (p = 0.006) and 425% (p = 0.015), respectively, but the mean reciprocal reaction time decreased by 7%. In addition, there were correlations between sleepiness and postural control variables with opened eyes (r = 0.616, 95% confidence interval [CI] = 0.361-0.815; r = 0.538; 95% CI = 0.280-0.748) and closed eyes (r = 0.557; 95% CI = 0.304-0.764, r = 0497; 95% CI = 0.325-0.715) and a pronounced effect of sleepiness on postural sway (R2 = 0.393; 95% CI = 0.001-0.03). Therefore, 12-h night work system and sleepiness showed a negative impact in postural and psychomotor vigilance performance of night workers. As unexpected, the force platform was feasibility to detect sleepiness in this population, underscoring the possibility of using this method in the workplace to prevent occupational injuries and accidents.

Adaptation of sensorimotor coupling in postural control is impaired by sleep deprivation

The purpose of the study was to investigate the effects of sleep deprivation (SD) in adaptation of the coupling between visual information and body sway in young adults’ postural control due to changes in optic flow characteristics. Fifteen young adults were kept awake for approximately 25 hours and formed the SD group, while fifteen adults who slept normally the night before the experiment participated as part of the control group. All participants stood as still as possible in a moving room before and after being exposed to one trial with higher amplitude and velocity of room movement. Postural performance and the coupling between visual information, provided by a moving room, and body sway were examined. Results showed that after an abrupt change in visual cues, larger amplitude, and higher velocity of the room, the influence of room motion on body sway was decreased in both groups. However, such a decrease was less pronounced in sleep deprived as compared to control subjects. Sleep deprived adults were able to adapt motor responses to the environmental change provided by the increase in room motion amplitude. Nevertheless, they were not as efficient as control subjects in doing so, which demonstrates that SD impairs the ability to adapt sensorimotor coupling while controlling posture when a perturbation occurs.

The filtering of the posturographic signals shows the age related features

Objective. Lower frequencies of slow oscillations of the posturographic signals can be removed using high-pass filtering. This procedure releases postural reflexes possessing higher frequencies and lower amplitude range. Mutual dependence between the x and y components of posturographic signals was analyzed using principal component analysis (PCA). The posturographic signals of old patients with idiopathic gait disturbance were compared with the control group of similar age and with younger patients. There was also the analysis of the influence of the eyes state (open versus closed) and the head position (normal or bent back). The statistically significant differences in the mutual dependence between x and y components between the groups of patients were analyzed using MANOVA. The significant differences were observed mainly in the range of filter frequencies f = 0.1–1.5 Hz and f = 2.2–5.5 Hz with a maximum effect at approximately 4-5 Hz. A detailed post-hoc analysis is also presented. The differences in the higher frequency range suggest the main disturbance to be connected with the spinal reflexes. Visual and vestibular support appear insufficient for postural stability control in the idiopathic gait disturbance group. The results suggest that idiopathic gait disturbance is the final stage of the aging process of postural system.

The effect of extended wake on postural control in young adults

The sleep-wake cycle is a major determinant of locomotor activity in humans, and the neural and physiological processes necessary for optimum postural control may be impaired by an extension of the wake period into habitual sleep time. There is growing evidence for such a contribution from sleep-related factors, but great inconsistency in the methods used to assess this contribution, particularly in control for circadian phase position. Postural control was assessed at hourly intervals across 14 h of extended wake in nine young adult participants. Force plate parameters of medio-lateral and anterior-posterior sway, centre of pressure (CoP) trace length, area, and velocity were assessed with eyes open and eyes closed over 3-min periods. A standard measure of psychomotor vigilance was assessed concurrently under constant routine conditions. After controlling for individual differences in circadian phase position, a significant effect of extended wake was found for anterior-posterior sway and for psychomotor vigilance. These data suggest that extended wake may increase the risk of a fall or other consequences of impaired postural control.