In a randomized controlled trial (RCT) of OSA patients (18), a group that performed oropharyngeal exercises for 30 minutes a day for three months reduced the average apnea hypopnea index (AHI, the number of apnea and hypopnea events per hour of sleep) by almost 35% (22.4 to 14.7, P < 0.05). The exercises consisted of isometric and isotonic exercises involving the tongue. Another RCT (19) designed to increase UA dilator muscle strength demonstrated that playing the didgeridoo (an aboriginal wind instrument) six times per week for an average of 25 minutes per day over four months decreased average AHI by almost 50% (22.3 to 11.6, P < 0.01). Electrical stimulation of the hypoglossal nerve (which innervates the GG) also promotes UA patency during sleep. Hypoglossal stimulation reduced UA resistance in both healthy persons and subjects with OSA and reduced AHI in OSA subjects by over 50% (20).