The effects of repeated transcranial direct current stimulation on sleep quality and depression symptoms in patients with major depression and insomnia

Although several strategies using transcranial direct current stimulation (tDCS) have been investigated to treat major depressive disorder (MDD), the efficacy of this treatment for patients with MDD who also have insomnia is unclear. To observe the effects of tDCS on sleep quality and depressive symptoms in patients with MDD who have insomnia. We conducted a randomized, double-blinded study involving adults with major depression and insomnia. We randomly assigned patients to either add tDCS or to sham tDCS to their regular treatment. After randomization, we treated a total of 90 patients at the Kangning Hospital, Ningbo, China. We allocated 47 patients to the tDCS group and 43 to the sham tDCS group. The tDCS treatment procedure included 20 sessions of 2-mA stimulation of the dorsolateral prefrontal cortex (DLPFC) for 30 min, which was followed by four weekly treatments. The anode and cathode electrodes were placed on the left and right DLPFC, respectively. We recorded the Self-rating Depression Scale (SDS), Self-rating Anxiety Scale (SAS), Pittsburgh Sleep Quality Inventory (PSQI), and Polysomnography (PSG) at Day 1 and Day 28. Compared with the sham tDCS group, the active tDCS group showed improved total scores of SAS and SDS. PSQI total score and all PSQI sub-divisions, except for "sleep duration and sleep efficiency," significantly improved after treatment. We also observed that tDCS affected sleep architecture, by increasing total sleep time and improving sleep efficiency through PSG. Our study demonstrated the effect of tDCS on sleep quality and depressive symptoms in patients with MDD and insomnia. These results suggested that tDCS stimulation not only improved symptoms of depression and anxiety but also had a positive effect on sleep quality in patients with MDD. For patients with depression and insomnia, tDCS stimulation could be a good supplement to drugs.