Repeated apneas during sleep can lead to a lack of oxygen in the body, and intermittent hypoxia can be damaging to multiple organs. Because apnea makes it difficult to fall into deep sleep or to wake up easily, deep sleep is significantly reduced and fragmentation of sleep occurs. If this condition persists it can cause serious damage to multiple systems and even sudden death. Common damages to the cardiovascular system include hypertension, heart failure, arrhythmia, coronary artery disease, and pulmonary hypertension; to the nervous system include stroke, cognitive decline, and neurodegenerative disease; to the digestive system, gastroesophageal reflux is common; and to the endocrine system, obesity, diabetes mellitus, and dyslipidemia are common. In addition, these patients have a very high risk of anesthesia during surgery, with a higher likelihood of asphyxia and more postoperative complications.