Effects of proprioceptive vibratory stimulation on body movement at 24 and 36h of sleep deprivation.

OBJECTIVE To investigate whether postural stability and adaptation differed after a normal night of sleep, after 24h (24 SDep) and 36h (36 SDep) of sleep deprivation while subjected to repeated balance perturbations. Also, to determine whether there was any correlation between subjective alertness scores and objective posturographic measurements. Lastly, to investigate the effects of vision on the stability during sleep deprivation. METHODS Body movements at five locations were recorded in 18 subjects (mean age 23.8years) using a 3D movement measurement system while subjected with eyes open and closed to vibratory proprioceptive calf stimulation after a normal night of sleep, 24 and 36 SDep. RESULTS The clearest sleep deprivation effect was reduced ability to adapt head, shoulder and hip movements, both with eyes open and eyes closed. Additionally, several near falls occurred after being subjected to balance perturbations for 2-3min while sleep deprived. Unexpectedly, postural performance did not continue to deteriorate between 24 and 36h of sleep deprivation, but showed some signs of improvement. Subjective scores of sleepiness correlated poorly with actual changes in postural control performance. CONCLUSIONS Sleep deprivation might affect postural stability through reduced adaptation ability and lapses in attention. Subjective alertness might not be an accurate indicator of the physiological effects of sleep deprivation. SIGNIFICANCE Sleep deprivation could increase the risk of accidents in attention demanding tasks. There is a need for objective evaluation methods to determine actual performance capacity during sleep deprivation.