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Slow-Wave Activity in Sleep Apnea Patients Before and After Continuous Positive Airway Pressure Treatment

Slow-Wave Activity in Sleep Apnea Patients Before and After Continuous Positive Airway Pressure TreatmentSleep apnea syndrome (SAS) is a chronic illness characterized by recurrent apneas and hypopneas during sleep, resulting in repetitive arousals and disruption of normal sleep architecture. Several studies have shown a strong deprivation of rapid eye movement (REM) sleep and of stages 3 and 4 nonrapid eye movement (NREM) sleep in SAS patients, even though their sleep efficiency seems to be preserved or minimally changed. Among the various symptoms associated with this condition, the most prevalent is excessive daytime sleepiness (EDS). Critical care
SAS is commonly treated with nasal continuous positive airway pressure (CPAP), which was found to restore normal airflow and sleep architecture and to suppress episodes of nocturnal hypoxemia. CPAP also improves daytime sleepiness as measured by the multiple sleep latency test (MSLT), especially with long-term use, although some degree of daytime somnolence remains.
According to a proposed model of sleep regulation, sleep and vigilance are regulated by two processes: a circadian process (process C) and a homeostatic process (process S). Slow-wave activity (SWA) is considered a marker or an objective measure of process S and has been shown, in normal subjects, to increase with the duration of prior wakefulness and to decline exponentially during the night from the first to the last sleep cycle. Unlike the quantification of slow-wave sleep, which requires an amplitude criterion (> 75 ?ьгжV) and a minimum quantity of these slow waves (20% of the epoch), SWA has no such criteria (thus also takes into account lower-amplitude slow waves and slow waves present in stage 2 sleep) and has a broader frequency definition (0.75 to 4.5 Hz).
Few studies have looked at the functioning of process S in various medical conditions except in narcolepsy, for which it was found to be enhanced. To our knowledge, the dynamics of SWA have never been studied across the night in SAS patients. It is expected that SWA will be decreased in SAS patients and the habitual dynamic of SWA decline across the night will be disrupted. We will also verify whether the EDS of untreated SAS patients is related to the decrease in SWA and whether CPAP treatment will restore a normal amount and pattern of SWA.