The apnea, the respiratory arrest during sleep:

Sleep apnea is, at a certain level of severity, a serious disease, that may cause not only sleepiness during the day but also serious systemic diseases.

The apnea is a total respiratory stop. The obstructive apnea is a complete occlusion of the respiratory tract whereas in case of the central apnea the central respiratory reflex arrests. The hypopnea is a reduction of the respiratory flow by more than 50%.

The apnea/hypopnea index, AHI is the degree of the severity of the disease. An apnea/hypopnea lasts at least 10 sec.

The apneas per hour sleep are counted, 10 apneas per hour result in an index of 10. An index of 0 to 5 is normal, 5 to 10 is a light, 10 to 20 a mid range and more than 20 a severe disease.

An obstructive apnea is characterized by an interruption of the very noisy snoring (rhonchopathy).

The central apnea, however, has no external signs