Changes of motor cortical excitability in human subjects from wakefulness to early stages of sleep: a combined transcranial magnetic stimulation and electroencephalographic study

The effect of sleep on human motor cortical excitability was investigated by evaluating the latency and amplitude of motor evoked potentials in en subject, using tran,cranial magnetic stimulation, Motor evoked potentials and electroencephalographic data were recorded simultaneously and analyzed. Recordings were performed before, during and after a sleep period. A significant decrease in motor evoked potentials amplitude and a slight change in motor evoked potentials latency were noted in the recordings during the different sleep stages with a return to baseline values on awakening. A decrease in motor cortical excitability is suggested as explaining the effect of sleep. (C) 2004 Elsevier Ireland Ltd. All rights reserved.