Obstructive sleep apnea (OSA) is a sleep disorder characterized by repeated interruptions in breathing due to the blockage of the airway during sleep. Common symptoms include loud snoring, gasping for air, excessive daytime sleepiness, and morning headaches. Risk factors include obesity, age, and anatomical features. Diagnosis usually involves a sleep study, and treatment options include lifestyle changes, CPAP machines, oral appliances, and sometimes surgery. It's important to seek medical advice if OSA is suspected.