One of the medications, atomoxetine, approved by the U.S. Food and Drug Administration (FDA) in 2002 for attention-deficit/hyperactivity disorder, increases levels of the excitatory neurotransmitter norepinephrine by blocking its reuptake (…). In sleep apnea patients, it’s known that the decline of norepinephrine during sleep contributes to a loss of tone among upper airway muscles, particularly the genioglossus. The other compound, called aroxybutynin, is a chemically tweaked form of a drug used to treat overactive bladder. It blocks certain receptors for acetylcholine, preventing this neurotransmitter from inhibiting the nerve that enervates genioglossus—effectively toning up the muscle during sleep.