Effects of transcranial direct current stimulation on performance and recovery sleep during acute sleep deprivation: a pilot study

Background: Previous studies claimed that transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) improves cognition in neuropsychiatric patients with cognitive impairment, schizophrenia, organic hypersomnia, etc, but few studies evaluated the effects of tDCS on cognitive improvement following sleep deprivation. The objective of this study was to determine whether tDCS (anode on the left DLPFC and cathode on the right DLPFC with a 2-mA current for 30 min) improves cognition following sleep deprivation. Methods: Seven participants received active tDCS and eight participants received sham tDCS when their cognition declined during at least 30 h of sleep deprivation. All participants completed the psychomotor vigilance task, Trail Making Tests A and B, digit cancellation test, Stroop color word test, the Brief Visuospatial Memory Test-Revised and a procedural game every 2 h during the sleep deprivation and after recovery sleep. Results: Compared to the sham stimulation, active tDCS (anode on the left DLPFC and cathode on the right DLPFC at a 2-mA current for 30 min) had beneficial effects on attention, memory, executive function, processing speed, and the ability to inhibit cognitive interference, and improved in subjective drowsiness and fatigue following sleep deprivation. The lasting effect of a single tDCS on cognition during sleep deprivation was greater than 2 h. In all participants, tDCS did not disturb recovery sleep, and cognitive performance recovered to the baseline levels after recovery sleep. Conclusions: The study results indicate that tDCS can improve cognition following sleep deprivation and does not disturb recovery sleep or cognitive performance after recovery sleep. The possible pathophysiological mechanisms might be related to the modulation of the corticothalamic pathway. We believe that tDCS can be applied in the treatment of sleep disorders involving sleepiness. Trial registration number: ChiCTR2000029420. Date of registration: 2020-1-31. (C) 2021 Elsevier B.V. All rights reserved.