Efeito da privação de sono no controle postural e na estabilidade dinâmica em adultos jovens saudáveis

Abstract

Postural control is a behavior that results from the contribution of many interacting systems(1,2). In this context, studies have analyzed this behavior by means of tools that recognize its complexity. These tools allow a global analysis of the movement pattern(1–5). Among them, the analysis of the regularity of the postural control has been widely used to reveal how disturbances affect this behavior(1,5–7). Some studies have shown that sleep deprivation (SD) can disturb both static postural control and the physical performance of healthy individuals(8–12). However, these studies used analysis that did not consider the complexity of the postural control in their investigations. Thus, it is still necessary to investigate whether the changes induced by PS modify postural control’s regularity since this tool has the potential to provide more information about this behavior(13). Also, the SD may affect the dynamic stability differently, since a static measure of posture is not related to its dynamic counterpart(14). However, few studies investigate the effects of PS on dynamic postural stability. Therefore, this study aimed to investigate the effects of 24-hour SD on dynamic stability and postural control, not only through classical measures of postural control, but also through the analysis of its regularity. Method: Seventeen young, healthy men (23.4 ± 3.7 years; 72 ± 13.4 kg 1.75 ± 6.7 m) participated in the study. They remained 24h in SD, while monitored, and six postural control measurements were made on a force plate (center of pressure). In addition, the Modified Star Excursion Balance Test (SEBTm) was applied at the beginning and end of the SD period to evaluate the individual’s dynamic stability (15). The regularity of the postural control was measured by the sample entropy analysis (SE)16. In the SEBTm, the lower limb composite score was used(13). Results / Conclusion: Repeated measures analysis of the variance (ANOVA) indicated a decrease in SE when comparing the first postural control measure (8:00 am) to the last one (8:00 am the following day) (p = 0.001), and the first (8:00h am) to the fourth (02: 00h am) (p = 0.032). There was a significant main effect for the area (p = 0.012) and speed (p = 0.007) of the center of pressure, but no differences were found in the pairwise comparisons among the time of the measurements. These findings demonstrate that individuals increased the regularity of their postural oscillations around 02:00 am (18h of SD). This specific change in behavior was only captured by the SE analysis. The paired t-test identified a significant difference in the composite score of the left lower limb (p = 0.033), with no difference being found in the right one (p = 0.076), indicating that the non-dominant lower limb was more affected by SD. This study revealed that SD reduced the adaptive capacity of healthy individuals to accomplish a postural control task. This result indicates that tools that investigate the postural control more globally were more sensitive to changes than the ones classically used.