ObjectiveTo assess the polysomnographic characteristics of insomnia patients with comorbid obstructive sleep apnea-hypopnea syndrome (OSAHS). MethodsWe performed a comparative analysis on the polysomnographic features among patients with pure insomnia (n=80), patients with pure OSAHS (n=80), and patients with insomnia and OSAHS (n=50) between August and December 2013. ResultsCompared with OSAHS group, patients with insomnia and comorbid OSAHS had a higher percentage of female, older age, lower body mass index, shorter total sleep time during the night, longer sleep latent period and wake after sleep onset (WASO), lower sleep efficacy, lower arousal index and apnea hypoventilation index (AHI), higher average and the lowest oxygen saturation of blood, lower Epworth Sleepiness Scale scores and sleep perception (P < 0.05). Compared with the insomnia group, patients with insomnia and comorbid OSAHS had a lower percentage of female, shorter total sleep time, lower sleep efficacy, longer WASO and higher AHI (P < 0.05). ConclusionPatients with insomnia and comorbid OSAHS have all the characteristics of insomnia and OSAHS patients:nocturnal hypoxia, sleep fragmentation, broken sleep continuity, decreased sleep efficiency, damaged perception of sleep time and sleep perception.