Sleep disordered breathing refers to a group of disorders that occur during sleep and involve a momentary, often cyclical, breathing noise (snoring), reduction (hypopnea), or cessation (apnea) of breathing which results in reduced blood oxygen levels or increased blood carbon dioxide levels. Repeat episodes or awakening from sleep is referred to as upper airway resistance syndrome, with multiple arousals from sleep throughout the night, often leading to fragmented and inefficient sleep. Sleep disordered breathing is a continuum of disorders ranging in spectrum from mild snoring to severe obstructive sleep apnea (OSA).