Changes in postural control during a 48-hr. sleep deprivation period.

Sleep deprivation has detrimental effects on cognitive abilities; however, there has been limited investigation into the effects of sleep deprivation on postural control or influence of time of day on postural control measures. Therefore, we measured postural control on a force plate every 6 hr. in 24 subjects (11 women, 13 men; M age 20 +/- 2.1 yr.; M height 1.68+/-0.29 m; body mass 63.3 +/- 28.7 kg) participating in a 48-hr. dance marathon. During the first 24-hr. period, postural control significantly worsened. Rather than a steady decrease in postural control, during the second day of the event a repeating oscillatory trend of fluctuations in postural control was observed for both days of the event. We hypothesize that the repeating oscillation of postural control followed a circadian rhythm pattern, suggesting that sleep deprivation for 48 hr. does not influence measures of postural control in a consistent manner. The apparent influence of time of day on postural control measures warrants consideration of this factor when conducting studies with repeated measures of postural control across different days.