A method and device for creating an afferent stimulus for preventing obstructive sleep apnea are disclosed. The device includes at least one electrode and a stimulator, of which at least one electrode stimulates the genioglossus muscle of a patient having obstructive sleep apnea. The electrode is capable of conducting selected electrical stimulation generated by the stimulator, and the system is capable of delivering the selected electrical stimulation during a selected time of day. The electrical stimulation is selected to maintain sufficient muscle tone of the genioglossus muscle to prevent it from obstructing the airway during sleep, preferably at a stimulus intensity low enough to avoid awakening the patient during sleep. A removable mouthpiece having a battery, at least one electrode, and a controller, and optionally a sensor, can be used for providing the stimulation.