An important concept in the biology of sleep is sleep apnea. Sleep apnea occurs at most withtin 20% on the general population. It is a sleep disorder caused by a blockage of the airway during sleep. Sleeping with sleep apnea includes: snoring loudly, gasping for air, and sometimes a halt in breathing for more than 20 seconds. A lack of oxygen and a buildup of carbon dioxide leads to multiple problems including: night sweats, weight gain, hearing loss, irregular heartbeat, and most of all fatigue during the day. Lots of people are not aware of the fact that they have sleep apnea until they go see their doctor and describe some of the symptoms like being tired and gaining weight. Sleep apnea is important to understand and deal with because it raises the overall risk of death by 17%! Children with sleep apnea usually just get their tonsils removed, but for adults with sleep apnea removal of the tonsils usually doesn't work. Thus, many adults with sleep apnea wear a face mask when they sleep that blows air into their nasal passages, forcing the airway to stay open. My stepfather has sleep apnea and has to wear a face mask every night even when we go on vacations. Unfortunately, sleep apnea may not be something adults can get rid of easily, bu there are methods to help ease their sleep, lessen their risk of death, and decrease the feeling of fatigue. I do still wonder though why removing the tonsils of an adult does not usually work to eliminate sleep apnea.