Transcranial Direct Current Stimulation (tDCS) involves delivering a weak electric current through two electrodes secured to a patient's head. Studies have suggested that tDCS may improve symptoms of ADHD and other mental health conditions.
Such findings prompted researchers to conduct a review to determine whether tDCS could be an effective treatment for insomnia. Their findings were published in the July 2016 Journal of Sleep Medicine & Disorders.
The three types of tDCS
tDCS can deliver stimulation in three ways:
- Anodal stimulation: This increases activity in the area being stimulated.
- Cathodal stimulation: This decreases activity in the area being stimulated.
- Sham stimulation: This emits a brief current and is used as a control in experiments.
The hyperarousal link
Since some cases of insomnia may be tied to hyperarousal, it makes sense to consider that cathodal stimulation (designed to decrease brain activity) may improve sleep. However, as the authors of the JSMD review pointed out, no studies have explored the effectiveness of tDCS for the treatment of insomnia. That being said, studies have looked at how tDCS can affect sleep.
How tDCS affects sleep duration
Researchers identified one study that found anodal stimulation (increasing activity) reduced total sleep time compared to cathodal and sham stimulation. Unfortunately, the study found that cathodal stimulation (decreasing activity) did not have a significant effect on total sleep time.
The study involved only healthy sleepers who were already getting adequate sleep. Perhaps the results would have been different if the study involved those living with insomnia who were in need of additional sleep time.
Combining different types of stimulation
The review’s authors mentioned another study involving individuals with bipolar disorder. The tDCS treatment combined anodal stimulation targeted at one area of the brain (the cerebellum) with cathodal stimulation targeted at a different area of the brain (the left dorsolateral prefrontal cortex). After treatment, participants demonstrated significant improvements in:
Can tDCS improve insomnia symptoms?
Studies do suggest that tDCS can alter sleep, but more studies are needed before it can be recommended as an insomnia treatment. As pointed out by the authors of the review, we need to see more studies demonstrate the impact of tDCS on insomnia and we need more research on how and why stimulating certain parts of the brain appears to affect sleep.
Is tDCS safe?
The most recent evidence-based update concluded that the use of conventional tDCS protocols in human trials did not produce any reports of a Serious Adverse Effect or irreversible injury across 33,200 sessions and 1,000 subjects with repeated sessions. However, until tDCS is found to be an effective method for improving insomnia symptoms, it’s probably best to pursue other, proven insomnia treatments.