Comorbid insomnia and obstructive sleep apnea in military personnel: Correlation with polysomnographic variables

Objectives: Military personnel undergoing polysomnography are typically diagnosed only with obstructive sleep apnea (OSA). Comorbid insomnia with OSA is a well-established, underappreciated diagnosis. We sought to determine if military personnel with mild OSA met clinical criteria for insomnia and if there was a pattern of polysomnogram (PSG) variables that identified insomnia in these patients. Methods: Retrospective chart review of military personnel with mild OSA; cluster analysis to describe PSG variables. Results: 206 personnel assessed, predominately male (96.6%), mean age 36.5 ± 8.14 years, body mass index 30.2 ± 3.66 kg/m² and apnea hypopnea index of 8.44 ± 2.92 per hour; 167 (81.1%) met criteria for insomnia. Cluster analysis identified a group of patients (N = 52) with PSG variables of increased wakefulness after sleep onset 77.3 minutes (27.7) (p < 0.001) and decreased sleep efficiency 82.6% (5.82) (p < 0.001) consistent with insomnia. Patients in this group were more likely to meet criteria for insomnia with an odds ratio 5.27 (1.20, 23.1), (p = 0.009). Conclusions: The majority of military personnel with mild OSA meet criteria for insomnia. Roughly one-third of these patients can be identified by a pattern of PSG variables. Recognizing and treating both comorbid insomnia and OSA could improve clinical outcomes.