In the absence of central apnea, any sudden drop in oxygen or excess of carbon dioxide, even if small, strongly stimulates the brains respiratory centers to breathe; the respiratory drive is so strong that even conscious efforts to hold ones breath do not overcome it.In pure central sleep apnea, the brains respiratory control centers, located in the region of the human brain known as the pre-Botzinger complex, are imbalanced during sleep and fail to give the signal to inhale, causing the individual to miss one or more cycles of breathing. The neurological feedback mechanism that monitors blood levels of carbon dioxide and in turn stimulates respiration fails to react quickly enough to maintain an even respiratory rate, allowing the entire respiratory system to cycle between apnea and hyperpnea, even for a brief time following an awakening during a breathing pause. The sleeper stops breathing for up to two minutes and then starts again. There is no effort made to breathe during the pause in breathing: there are no chest movements and no muscular struggling, although when awakening occurs in the middle of a pause, the inability to immediately operate the breathing muscles often results in cognitive struggle accompanied by a feeling of panic exacerbated by the feeling associated with excessive blood CO2 levels. Even in severe cases of central sleep apnea, however, the effects almost always result in pauses that make breathing irregular rather than cause the total cessation of breathing over the medium term.
Arava, Aravah or Arabah may refer to:

Places
Arava, Estonia, a village in Anija Commune, Harju County, Estonia
Arava(h) (Hebrew) or Arabah (Arabic), a section of the Great Rift Valley between the Dead Sea and the Gulf of Aqaba in Israel and Jordan

Other uses
Arava Institute for Environmental Studies, an Israeli study programme
Arava Power Company, an Israeli solar energy company
Arava Shahaf (born 1990), Israeli footballer
Arava spider, a huntsman spider found in the southern Arava Valley of Israel and Jordan
Arava, a brand name for the antirheumatic drug leflunomide
IAI Arava, a plane manufactured by Israel Aircraft Industries
Aravah (Sukkot), a willow branch, one of the Four Species used on the Jewish holiday of Sukkot

See also
Arraba (disambiguation)
Araba (disambiguation)