Effect of sleep deprivation on gait complexity.

Gait complexity is considered an indicator of adaptability, reflecting the complex interaction between multiple components of the neuromuscular system. Previous research provided evidence that chronobiology, which reflects the individual expression of circadian rhythms, affects the regulation of gait dynamics. The literature also suggests the disruption of these circadian rhythms affects multiple human physiological systems. Considering the association between chronobiology and gait complexity, and its clinical relevance, it would be important to investigate whether the disruption of sleep-wake cycle could affect gait complexity. This study aimed to investigate the effect of 1 night of sleep deprivation on gait complexity and variability of healthy individuals, exploring potential implications for motor control. Seventeen healthy and young male adults underwent an in-lab supervised 24-hr sleep deprivation protocol, with gait complexity and variability assessed using detrended fluctuation analysis and coefficient of variation, respectively. Chronotype was also assessed through the Morningness-Eveningness Questionnaire. We observed a loss of gait complexity with sleep deprivation (PRE: 0.8 ± 0.13; POST24: 0.62 ± 0.08, p < 0.001), while gait variability remained unaltered (p = 0.132). Additionally, we demonstrated an association between gait complexity's relative changes and chronotype (r = -0.665, p = 0.004). Overall, our findings suggest sleep deprivation induces a decrease in the neuromuscular system's ability to flexibly adapt gait output. Moreover, we also highlight the importance of chronobiology in motor control, as we observed the more morning-type an individual is, the greater the loss of complexity following 1 night of sleep deprivation. Altogether, our findings underscore the potential impact of sleep deprivation on central processes underlying gait complexity.