Insomnia in Patients with Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea syndrome (OSAS) is a common sleep disorder. Insomnia complaint is the most common sleep disorders in the general population. The association between OSAS and insomnia symptom has received little attention from sleep investigators in the past few decades. This study investigates the prevalence of insomnia symptoms and related factors in patients with OSAS.

This is a retrospective study of 151 consecutive patients with OSA who underwent sleep polysomnography. Patients were interviewed about their detailed sleep history. Insomnia and subjective daytime sleepiness was assessed using the Insomnia Severity Index and Epworth Sleepiness Scale. Polysomnographic recordings were compared in patients with and without insomnia symptom.

Insomnia was a common complaint in patients being evaluated for obstructive sleep apnea. Among 151 patients with OSAS diagnosis, 81.7% of patients complained from one of the four insomnia symptom, 33.4% reported difficulty in falling sleep, 38.8% difficulty in sleep maintenance and 31.4% early morning awakening. Only 29.3% of patients were satisfied with their sleep quality. No significant association found between the insomnia symptom and mean nocturnal saturation of oxygen (P>0.05).

Insomnia is a common complaint in the patients suffering from OSAS. There was no relationship between insomnia symptom and severity of apnea or oxygen desaturation. Thus, nocturnal hypoxia is less likely to explain the high prevalence of insomnia among patients with OSAS.