A device (103) for applying an electrical stimulation to one or more muscles of the mouth of the user, the device (103) includes one or more electrodes (132, 133) for applying electrical stimulation to one or more muscles of the mouth of a user and a sensor (140a, 140b, 141a, 141b) for determining the muscle tone of the tongue of the user. Also disclosed are methods and systems for determining a stimulation plan.