Robust evaluation of time since awakening using force platform posturography

Abstract

Introduction: Sleepiness is responsible for a considerable proportion of traffi c accidents. It is thus an important traffi c safety issue to fi nd a robust, objective and practical way to estimate the amount of time a person has been awake. To attempt to meet this goal, we investigated the relationship between sleepiness and posture control. Methods: Subjects were kept awake for 36 hours and posturographic data during quiet standing were collected every two hours by means of a force platform. The standing surface (rigid surface or foam surface) and visual (eyes open or eyes closed) conditions were manipulated. Results: In the more challenging conditions (with foam surface and/or eyes closed), the body sway variables derived from the center of the pressure measurement increased signifi cantly when time since awakening became greater than 21 h in almost all subjects. Conclusion: Based on this result, we propose a practical protocol that could robustly assess whether time since awakening was greater than 21 h.

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

“…The generalization of the results may be limited because of the prevalence of women in the study sample (75%). However, similar results were obtained in studies with a prevalence of men [ 18 , 28 ], which likely minimizes this limitation. Another limitation was that controls for the circadian period were not used in the measurements because the work schedule was not flexible.…”

“…A total of two tests were conducted, with two replicates and a 1-min interval between each replicate [ 27 ]. Each measurement of postural control on the force platform lasted 30 seconds [ 18 , 27 , 28 ], the participants were instructed to stare at a black target approximately 5.0 cm in diameter, positioned on a white wall at eye level at a distance of 2.0 meters. The reaction force and moments of force on the force platform were acquired using an acquisition card (NI BNC-2090, National Instruments, Inc.) at a frequency of 100 Hz [ 27 , 28 ].…”

Chronic Low Quality Sleep Impairs Postural Control in Healthy Adults

“…The more difficult tests that had different platform stability levels (dynamic test 2) showed significant differences between groups with eyes closed but not with eyes open, and similar results were reported for PC tests after one night SD [ 17 – 23 ]. This suggests that lack of vision impairs postural balance more deeply in subjects with chronic problems of sleep quality, maybe due to disturbances in the brain sensory integration areas.…”

“…This finding means that subtle (and often neglected) loss of sleep quality results in a loss of performance of an important motor task such as posture control with eyes closed. Although it was proven that PC was affected by one day of complete SD [ 8 – 23 , 35 , 36 ], this is the first study showing posture deterioration that could be attributed to a chronic decrease in the sleep quality monitored for more than one week.…”

“…Several studies reported that PC deteriorated after one night without sleep [ 8 – 16 ]. However, other studies only found significant differences in PC with sleep deprivation (SD) when the eyes were closed [ 17 – 23 ]. It is well-known that PC performance decreased with eyes closed [ 24 ] and this effect might be accentuated with SD [ 17 – 23 ].…”