386 Sleep-Wake Disorders
Functional Consequences of Central Sleep Apnea
Idiopathic central sleep apnea has been report ed to cause symptoms of disrupted sleep, in-
cluding insomnia and sleepines s. Cheyne-Stokes breathing with comorbid heart failure
has been associated with excessive sleepine ss, fatigue, and insomnia, although many in-
dividuals may be asymptomatic. Coexistence of heart failure and Cheyne-Stokes breath-
ing may be associated with increased card iac arrhythmias and increased mortality or
cardiac transplantation. Individuals with central sleep apnea comorbid with opioid use
may present with symptoms of sleepiness or insomnia.
Differential Diagnosis
Idiopathic central sleep apnea must be distinguished from other breathing-related sleep
disorders, other sleep disorders, and medical conditions and mental disorders that cause
sleep fragmentation, sleepiness, and fatigue.  This is achieved using polysomnography.
Other breathing-related sleep disorders and sleep disorders. Central sleep apnea can
be distinguished from obstructive sleep apne a hypopnea by the presen ce of at least five
central apneas per hour of sleep. These condit ions may co-occur, but central sleep apnea is
considered to predominate when the ratio of central to obstructive respiratory events ex-
ceeds 50%.
Cheyne-Stokes breathing can be distinguishe d from other mental disorders, including
other sleep disorders, and othe r medical conditions that caus e sleep fragmentation, sleep-
iness, and fatigue based on the presence of a predisposing condition (e.g., heart failure or
stroke) and signs and polysomnographic evidence  of the characteristic breathing pattern.
Polysomnographic respiratory findings can help distinguish Cheyne-Stokes breathing
from insomnia due to other medical conditio ns. High-altitude periodic breathing has a