Hypoventilation
The state in which a reduced amount of air enters the alveoli in the lungs, resulting in decreased levels of oxygen and increased levels of carbon dioxide in the blood.
Hypoventilation can be due to breathing that is too shallow (hypopnea) or too slow (bradypnea) or to diminished lung function.
The opposite of hypoventilation is hyperventilation (overbreathing).
See also: Congenital central hypoventilation syndrome.