Hamza O Dhafar,1 Ali A Awadh,2 Salih A Aleissi,1 Galal Eldin Abbas Eltayeb,3 Samar Z Nashwan,1 Ahmed S BaHammam1,4 1The University Sleep Disorders Center, Department of Medicine, College of Medicine, King Saud University, Riyadh, Saudi Arabia; 2Seha Virtual Hospital, Ministry of Health, Riyadh, Saudi Arabia; 3Department of Management Information Systems, College of Business and Economics, Qassim University, Buraydah, Saudi Arabia; 4The Strategic Technologies Program of the National Plan for Sciences and Technology and Innovation in the Kingdom of Saudi Arabia, Riyadh, Saudi ArabiaCorrespondence: Ahmed S BaHammam, University Sleep Disorders Center, Department of Medicine, College of Medicine, King Saud University, Box 225503, Riyadh, 11324, Saudi Arabia, Email [email protected]: Data on the prevalence and correlates of rapid eye movement (REM)–related obstructive sleep apnea (REM-OSA) in narcolepsy remains limited. This study aimed to assess the prevalence and independent associated factors with OSA and REM-OSA in patients with narcolepsy, and to compare the distribution of REM-OSA between patients with narcolepsy and matched controls without narcolepsy.Patients and Methods: This retrospective study of a prospectively collected cohort included 190 adult patients with narcolepsy (narcolepsy type 1 [NT1] = 119, narcolepsy type 2 [NT2] = 71) who underwent polysomnography and multiple sleep latency test at the University Sleep Disorders Center, King Saud University Medical City, between January 2007 and February 2022. REM-OSA was defined as an apnea–hypopnea index (AHI) ≥ 5, AHI-REM/AHI–non–rapid eye movement (NREM) ≥ 2, AHI-NREM < 8, and REM sleep duration > 10.5 minutes. A total of 106 patients with narcolepsy were diagnosed with OSA. A control group of 122 patients with OSA but without narcolepsy, matched by age, sex, AHI, and BMI, was used for comparison. Logistic regression identified independent associated factors with OSA and REM-OSA.Results: OSA was diagnosed in 106 patients with narcolepsy (55.8%). REM-OSA was present in 26.4% of these cases, with a slightly higher prevalence in NT2 (30%) than in NT1 (24%). REM-OSA showed a trend toward higher prevalence in the narcolepsy group compared to controls (26.4% vs 17.2%, OR: 1.73, 95% CI: 0.91– 3.27, p = 0.09). Male sex, BMI, and arousal index were independent correlates of OSA among patients with narcolepsy. REM-OSA was independently associated with arousal index and REM sleep duration.Conclusion: OSA and REM-OSA are common in patients with narcolepsy. REM-OSA was more prevalent in the narcolepsy group than in matched controls, suggesting a potential association between narcolepsy and REM-OSA that warrants investigation in larger cohorts.Plain Language Summary: People with narcolepsy often struggle with excessive daytime sleepiness and disrupted nighttime sleep. When another sleep disorder, such as obstructive sleep apnea (OSA), occurs alongside narcolepsy, it can make symptoms worse. A specific form of OSA, known as REM-OSA (which primarily occurs during rapid eye movement sleep), has been associated with an increased risk of heart and metabolic conditions. However, studies examining REM-OSA in people with narcolepsy remain limited.In this study, we evaluated 190 adults with narcolepsy and found that more than half had OSA. Among those with OSA, over one in four also had REM-OSA. We compared these patients to a group of individuals who had OSA but not narcolepsy. The two groups were matched by age, sex, apnea severity, and body mass index (BMI). We found that REM-OSA was more common in people with narcolepsy than in the matched controls. Although the difference was not statistically significant, the trend suggests a possible link worth further investigation.Understanding the relationship between narcolepsy and REM-OSA is important for improving diagnosis and treatment. A better understanding of this overlap may help improve patient outcomes. More research in larger groups is needed to confirm this connection.Keywords: sleep-disordered breathing, REM sleep, arousal index, sleep fragmentation, polysomnography, multiple sleep latency tes
