The most common cause of snoring is sleep apnea, which is a condition where a person's breathing is interrupted during sleep. Sleep apnea is caused by the narrowing or blockage of the airway, which can be caused by a variety of factors such as obesity, smoking, alcohol consumption, and allergies. Treatment for sleep apnea usually involves lifestyle changes such as weight loss, quitting smoking, and avoiding alcohol. In more severe cases, a CPAP machine may be used to help keep the airway open during sleep.