Incidence of Insomnia in OSA patients and its correlations with parameters of polysomnography

Background/Aims: Prevalence of insomnia in obstructive sleep apnoea (OSA) patients has been estimated in many studies and has been found to be a frequent symptom (38% in a recent review 1).Our study aims to estimate the incidence of insomnia in Greek patients presenting to a public hospital sleep clinic, and correlate it with the severity of OSA and parameters of polysomnography (PSG). Methods: 100 patients who visited the sleep unit of the General Hospital ‘Evangelismos’ completed the Athens Insomnia Scale (AIS) and underwent a polysomnographic study. 56% were men, with mean age 54,7±12,5 years and BMI 31,5±6,2. Results: 70% of patients had insomnia. Insomnia (AIS≥6) and OSA (AHI≥5) were coexistent in 71,4 %. There was no correlation between insomnia and severity of OSA. A strong positive correlation was found/evident between difficulty in initiating sleep and number of hypopneas (r: 0,20 p:0,049), diminished functioning during the day and leg movements (r:0,21 p:0,050) and between daytime sleepiness and wake after sleep onset (WASO) (r:0,2 p:0,038). A negative correlation was found between overnight awakenings and sleep efficiency (r: -0,23 p: 0,021). Also, negative correlation was found between early morning awakening and minimum SpO2 (r=0.27, p=0,021), and between insufficient duration of sleep (r:-0,22 p: 0,021) and minimum SpO2. Conclusions: We found a high incidence of insomnia in patients with OSA, which does not correlate with severity of OSA. Contrary to many other studies, insomnia was not more common in women. More studies are required to clarify the significance of the positive correlation between insomnia and number of hypopneas and minimum SpO2.