Can Noninvasive Brain Stimulation Improve Sleep in Adults With Insomnia?

In patients with insomnia, noninvasive brain stimulation (NIBS) represents a safe and effective alternative to pharmacologic treatments, according to the findings of a study published in Sleep Science and Practice.

Insomnia, a prevalent disorder affecting up to 30% of adults worldwide, is commonly managed with medications, but their efficacy is limited and use can lead to dependency, tolerance, and other side effects. Cognitive behavioral therapy for insomnia (CBT-I) is a nonpharmacologic alternative to sleep medications, but there are widespread barriers to treatment.

To address these limitations, researchers conducted a systematic review to evaluate the efficacy and safety of NIBS techniques, specifically repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), and transcranial alternating current stimulation (tACS), for improving sleep quality in adults with insomnia.

A total of 43 studies published from inception to December 2024 were included from PubMed, Scopus, and Web of Science databases. Eligible studies involved adult patients with primary or comorbid insomnia who received at least 1 form of NIBS and reported outcomes using either subjective sleep assessments (the Pittsburgh Sleep Quality Index or Insomnia Severity Index) or objective methods (polysomnography or actigraphy). Each study was critically appraised using the Joanna Briggs Institute tool for experimental and quasi-experimental studies.

Overall, rTMS showed the most consistent and robust benefits across studies. Low- and high-frequency rTMS targeting the dorsolateral prefrontal cortex (dlPFC), parietal areas, or angular gyrus led to improvements in sleep onset, continuity, and efficiency. Some trials found that rTMS improved objective EEG sleep parameters in patients with depression, Parkinson disease, or post-stroke insomnia.

tDCS was also associated with improved sleep quality, particularly when targeting the dlPFC. Studies in patients with traumatic brain injury (TBI) or major depressive disorder showed significant reductions in insomnia severity and increased deep sleep. However, results varied, and some trials reported limited benefit depending on baseline arousal levels or psychiatric comorbidities.

tACS, especially when applied in the theta or alpha frequency bands before sleep, demonstrated efficacy in reducing sleep latency and enhancing total sleep time. Personalized stimulation based on individual EEG profiles showed greater benefit compared to fixed-frequency protocols.

Most interventions were well-tolerated, with few adverse effects reported. Compared with rTMS, tDCS and tACS exhibited fewer side effects, likely due to their lower stimulation intensities.

Study limitations include heterogeneity in stimulation parameters, subjectivity of sleep quality measures, lack of sham controls in some trials, and the limited number of tDCS and tACS studies compared to rTMS.

“NIBS represents a revolutionary advancement in the treatment of insomnia, offering non-invasive, safe, and highly adaptable interventions that address both the neural and psychological dimensions of sleep disorders,” the researchers concluded.

This research was supported personally by the study authors.