Department of Physics, University of Helsinki, Helsinki, Finland.
Gait Posture. 2013 Jun;38(2):192-7. doi: 10.1016/j.gaitpost.2012.11.011. Epub 2012 Dec 12.
Postural control during quiet stance is a common everyday physical activity. Sleepiness is increasingly prevalent in our 24-h society. Yet, little research exists that quantitatively links the fluctuations in sleepiness and postural control. This study quantifies the circadian amplitude and homeostatic buildup rate in postural control. With a force plate we assessed postural control in 12 participants (21-38 years) every 2h during 24h of sustained wakefulness. The sway area was 1.39 ± 0.71 mm(2) at the circadian high around noon, and 4.02 ± 0.67 mm(2) at the circadian low around 6 am (a 189% change, p=0.02). The circadian amplitude of the sway area was therefore 2.63 mm(2). The sway area was 1.92 ± 0.64 mm(2) at the start of the 24-h period and 4.42 ± 0.69 mm(2) at the end of the period (a 130% change, p<0.001). The homeostatic buildup rate of sway area was 0.04 h(-1). The circadian- and homeostatic effects on sway variability, sway velocity, sway frequency and fractal dimension were smaller but still significant. This study found that the circadian amplitude and homeostatic buildup rate are quantifiable from posturographic data, and that they have significant impact on postural control. This finding is important because it means that one could apply the framework of the famous two-process model of sleep regulation (published by Borbély in 1982) to explain the previously reported sleepiness-related changes in postural control.
姿势控制在安静站立时是一种常见的日常身体活动。在我们 24 小时的社会中，困倦越来越普遍。然而，很少有研究定量地将困倦和姿势控制的波动联系起来。本研究量化了姿势控制的昼夜振幅和内稳态积累率。使用力板，我们在 24 小时的清醒过程中每 2 小时评估 12 名参与者（21-38 岁）的姿势控制。在中午左右的昼夜高峰时，摇摆面积为 1.39 ± 0.71mm²，在早上 6 点左右的昼夜低谷时为 4.02 ± 0.67mm²（变化 189%，p=0.02）。因此，摇摆面积的昼夜振幅为 2.63mm²。在 24 小时周期的开始时，摇摆面积为 1.92 ± 0.64mm²，在周期结束时为 4.42 ± 0.69mm²（变化 130%，p<0.001）。摇摆面积的内稳态积累率为 0.04h⁻¹。摇摆变异性、摇摆速度、摇摆频率和分形维数的昼夜和内稳态效应较小，但仍具有统计学意义。本研究发现，从姿势图数据中可以量化出昼夜振幅和内稳态积累率，并且它们对姿势控制有显著影响。这一发现很重要，因为这意味着可以应用著名的睡眠调节两过程模型（由 Borbély 于 1982 年发表）的框架来解释先前报道的与困倦相关的姿势控制变化。
