High frequency repetitive transcranial magnetic stimulation (rTMS) of the left dorsolateral cortex: EEG topography during waking and subsequent sleep

Repetitive transcranial magnetic stimulation (rTMS) is a novel research too l in neurology and psychiatry. It is currently being evaluated as a conceiv able alternative to electroconvulsive therapy for the treatment of mood dis orders. Eight healthy young (age range 21-25 years) right-handed men withou t sleep complaints participated in the study. Two sessions at a 1-week inte rval. each consisting of an adaptation night (sham stimulation) and an expe rimental night (rTMS in the left dorsolateral prefrontal cortex or sham sti mulation; crossover design), were scheduled. In each subject, 40 trains of 2-s duration of rTMS (inter-train interval 28 s) were applied at a frequenc y of 20 Hz (i.e. 1600 pulses per session) and at an intensity of 90% of the motor threshold. Stimulations were scheduled 80 min before lights off. The waking EEG was recorded for 10-min intervals similar to 30 min prior to an d after the 20-min stimulations, and polysomnographic recordings were obtai ned during the subsequent sleep episode (23.00-07.00 h). The power spectra of two referential derivations, as well as of bipolar derivations along the antero-posterior axis over the left and right hemispheres, were analyzed. rTMS induced a small reduction of sleep stage 1 (in min and percentage of t otal sleep time) over the whole night and a small enhancement of sleep stag e 4 during the first non-REM sleep episode. Other sleep variables were not affected. rTMS of the left dorsolateral cortex did not alter the topography of EEG power spectra in waking following stimulation, in the all-night sle ep EEG, or during the first non-REM sleep episode. Our results indicate tha t a single session of rTMS using parameters like those used in depression t reatment protocols has no detectable side effects with respect to sleep in young healthy males. (C) 2001 Elsevier Science Ireland Ltd. All rights rese rved.