Abstract: Disclosed herein is a non-invasive intraoral neurostimulation device and method for treating obstructive sleep apnea (OSA) while improving adherence, effectiveness, and outcomes. The intraoral neurostimulation device includes a mouthpiece, at least one electrode pair having a reference electrode and a stimulating electrode supported by the mouthpiece, and a substrate positioned between a tongue of a user and the stimulating electrode. The intraoral neurostimulation device is configured to deliver non-invasive electrical neurostimulation to the motor neurons of at least one genioglossus muscle to induce a muscle contraction of the tongue, thereby eliminating the blockage and returning normal airflow to the user. In certain embodiments, the intraoral neurostimulation device is paired with a respiratory sensor to deliver stimulation synchronized with the respiratory rhythm of the user or deliver stimulation only during apneic episodes, reducing the total amount of stimulation time.