Decrease in motor cortical excitability in human subjects after sleep deprivation

The effect of sleep deprivation on human motor cortical excitability was in vestigated by evaluating the changes in motor evoked potentials from the th enar eminence muscles of the right hand in seven subjects. Motor threshold, motor evoked potential amplitude, silent period, intracortical inhibition, intracortical facilitation and F wave were studied. Recordings were perfor med every 6 h during the day-time (from 09.00 to 21.00 h) and every 3 h dur ing the night-time (from 21.00 to 09.00 h). Significant increases in motor threshold, intracortical inhibition and silent period were noted in the rec ordings during the night associated with a return to baseline values in the morning. No significant changes were observed in any of the other paramete rs. Enhancement of intracortical motor inhibition is suggested to explain t he effect of sleep deprivation. (C) 2001 Published by Elsevier Science Irel and Ltd.