[Surviving sleep: when the heart and brain are damaged by apnea]

Sleep apnea generally results from pharyngeal collapse and leads to the so-called obstructive sleep apnea syndrome (OSAS). OSAS is associated with excessive daytime sleepiness and chronic fatigue and has cardiovascular consequences. Acute hemodynamic changes during obstructive apnea are mainly due to sympathetic activation. These result from changes in blood oxygen and carbon dioxide content, as well as sleep fragmentation and intrathoracic pressure changes. Chronic consequences are linked to the sustained increase in sympathetic activity as well as endothelial dysfunction and vascular remodeling. These vascular changes seem to be a consequence of the oxidative stress and systemic inflammation associated with OSA. Metabolic impairment also plays a role. OSA increases the risk of hypertension, coronary heart disease, arrhythmias, sudden death and cardiovascular mortality. Continuous positive airway pressure (CPAP) has been the first-line treatment for the last 30 years, and partly prevents the excess cardiovascular morbidity and mortality.