Human Sleep Apneas and Animal Diving Reflexes: The Comparative Link.

Adaptations to survive periods of limited access to oxygen should have been favored along the evolution of vertebrates. Paradigmatic examples of this adaptation are the diving animals, which can sustain prolonged and repetitive periods of anoxia. These animals support what would be considered a severe gas imbalance in their internal environment thanks to three main strategies: increased oxygen stores, resistance to asphyxia, and reduced metabolic expenditure during the apneic intervals. However, diving animals developed their abilities from very old life-sustaining responses that should have been used on many other occasions. Humans with sleep apneas perhaps share many physiological adaptations with diving animals. We review here the extent of such similarities and offer clear evidence of its existence and suggest possible research lines that could improve the clinical knowledge about this condition.