Specify current severity:
Severity is graded according to the degree of hypoxemia and hypercarbia present dur-
ing sleep and evidence of end organ impairment due to these abnormalities (e.g., right-
sided heart failure). The presence of blood gas  abnormalities during wakefulness is an
indicator of greater severity.
Subtypes
Regarding obesity hypoventilati on disorder, the prevalence of obesity hypoventilation in
the general population is not known but is thought to be increasing in association with the
increased prevalence of obesity and extreme obesity.
Diagnostic Features
Sleep-related hypoventilation can occur in dependently or, more frequently, comorbid
with medical or neurological disorders, medi cation use, or substa nce use disorder. Al-
though symptoms are not mandatory to make this diagnosis, individuals often report
excessive daytime sleepiness, frequent arou sals and awakenings during sleep, morning
headaches, and insomnia complaints. 
Associated Features Supporting Diagnosis
Individuals with sleep-related hypoventilation  can present with sl eep-related complaints
of insomnia or sleepiness. Episodes of orth opnea can occur in individuals with diaphragm
weakness. Headaches upon awakening may be pr esent. During sleep, episodes of shallow
breathing may be observed, an d obstructive sleep apnea hypo pnea or central sleep apnea
may coexist. Consequences of ventilatory in sufficiency, includin g pulmonary hyperten-
sion, cor pulmonale (right heart failure), polycythemia, and neurocognitive dysfunction,