Cognitive Performance After Repeated Exposure to Transcranial Direct Current Stimulation (tDCS) During Sleep Deprivation.

Previously, our lab demonstrated a 6 h performance benefit after a single 30-minute transcranial direct current stimulation (tDCS) session. Medical research with tDCS shows beneficial effects of repeated exposures; therefore, we hypothesize that repeated exposures will extend to healthy populations. Four groups of twelve participants in each received either active stimulation at 1800 and sham at 0400 h, sham at 1800 and active at 0400 h, active stimulation at both 1800 and 0400 h, or sham at 1800 and 0400 h during 36 h of continued wakefulness. Every two hours beginning at 1800 and ending at 1900 h the next day, participants completed 4 cognitive tasks along with subjective questionnaires. Contrary to our hypothesis, repeating stimulation did not have an additive benefit to cognitive performance. However, participants did report feeling significantly less fatigued on the subjective questionnaires compared to the other groups; suggesting possible additive effects for improving subjective mood.