Stephen B. Simons ^* Maria Provo Alexandra Yanoschak Calvin Schmidt Isabel Gerrard Michael Weisend Craig Anderson Renee Shimizu Patrick Connolly

• Teledyne Scientific & Imaging, Durham, United States

The normal transition to sleep is characterized by a reduction in higher frequency activity and an increase in lower frequency activity in frontal brain regions. In sleep onset insomnia these changes in activity are weaker and may prolong the transition to sleep. Using a wearable device, we compared 30 minutes of short duration repetitive transcranial electric stimulation (SDR-tES) at 0.75 Hz, prior to going to bed, with an active control at 25 Hz in the same individuals. Treatment with 0.75 Hz significantly reduced sleep onset latency (SOL) by 53% when compared with pre-treatment baselines and was also significantly more effective than stimulation with 25 Hz which reduced SOL by 30%. Reductions in SOL with 25 Hz stimulation displayed order effects suggesting the possibility of placebo. No order effects were observed with 0.75 Hz stimulation. The decrease in SOL with 0.75 Hz treatment was proportional to an individual’s baseline wherein those suffering from the longest pre-treated SOLs realized the greatest benefits. Changes in SOL were correlated with left/right frontal EEG signal coherence around the stimulation frequency, providing a possible mechanism and target for more focused treatment. Stimulation at both frequencies also decreased perceptions of insomnia symptoms measured with the Insomnia Severity Index, and comorbid anxiety measured with the State Trait Anxiety Index. Our study identifies a new potential treatment for sleep onset insomnia that is comparably effective to current state-of-practice options including pharmacotherapy and cognitive behavioral therapy and is safe, effective, and can be delivered in the home.