Relationship of symptoms with sleep-stage abnormalities in obstructive sleep apnea-hypopnea syndrome

BACKGROUND: Patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) present with a variety of sleep-related symptoms. In polysomnography, sleep architecture is almost always abnormal, but it is not known which of the sleep-stage abnormalities are related to symptoms. Finding key sleep-stage abnormality that cause symptoms may be of therapeutic importance to alleviate symptoms. So far the mainstay of treatment is continuous positive airway pressure (CPAP)/bi-level positive airway pressure (BIPAP) therapy, but many patients are non-compliant to it. Correcting the sleep-stage abnormality that cause symptoms by pharmacotherapy may become an important adjunct to CPAP/BIPAP therapy. METHODS: A cross-sectional study. Adult subjects who attended a sleep laboratory for diagnostic polysomnography for a period of 1 month were recruited consecutively. OSAHS was diagnosed using American Academy of Sleep Medicine criteria. Subjects filled a questionnaire for symptoms prior to polysomnography. RESULTS: Thirty subjects, of whom 83.3% were obese, met diagnostic criteria, with males constituting 46.7% and females constituting 53%. Mean age was 53.40±11.60 years. Sleep architecture comprised N1 19.50±19.00%, N2 53.93±13.39%, N3 3.90±19.50%, and rapid eye movement 8.92±6.21%. Excessive fatigue or sleepiness, waking up tired, falling asleep during the day, trouble paying attention, snoring and insomnia were significantly related to decreased N3 sleep. CONCLUSIONS: Most of the symptoms in OSAHS in adults are related to decreased stage N3 sleep. If confirmed by larger controlled studies, correcting N3 sleep deficiency by pharmacotherapy may become an important adjunct to CPAP/BIPAP therapy to alleviate symptoms.