OBESITY-INDUCED BREATHING VARIABILITY DURING SLEEP IS NOT ENTIRELY ATTRIBUTED TO APNEAS AND SLEEP FRAGMENTATION

Abstract Introduction Obesity is a major cause of sleep-disordered breathing (SDB). Conventional metrics of SDB can be confounded by the effects of obesity on oxygenation and lack of standard definitions. Sleep fragmentation is frequently observed in obese individuals, but whether it occurs independently of SDB remains unknown. Quantitative analysis of ventilation may delineate the effects of obesity on breathing patterns and sleep fragmentation. We aimed to examine the effects of obesity on respiratory patterns during sleep and the relationship between obesity-related respiratory variability and sleep fragmentation. Methods Sleep recordings were performed in 15 lean C57BL/6J and 17 diet-induced obese (DIO) mice on the same genetic background. We applied Poincaré analysis of minute ventilation (VE) during sleep to estimate the breathing variability. Arousals were classified as respiratory when associated with ≥30% drops in VE from baseline. Results Breathing variability was significantly higher in DIO mice during NREM sleep, but not during REM sleep. Obesity-induced breathing variability could not be entirely attributed to apneas or arousals. Sleep fragmentation was 45% greater in DIO mice. Respiratory arousals comprised 15% of the arousals in both strains. Breathing variability was inversely associated with sleep fragmentation regardless of obesity. Conclusion Obesity increased respiratory variability during NREM sleep, which was not fully attributed to apneas and macro-sleep architecture. Obesity caused sleep fragmentation that was not entirely explained by SDB severity. Our quantitative analysis of VE identified differences in breathing variability in obesity that were not captured by traditional SDB metrics, which may be applicable for human SDB. Support (If Any) NHLBI NIH R01 HL135483, 2R01 HL133100-05, R01 HL128970, and R01 HL13892; NINDS NIH R01 NS112266; American Academy of Sleep Medicine Foundation 238-BS-20; American Thoracic Society Unrestricted Award; Johns Hopkins Blaustein Pain Research Grant; American Heart Association Postdoctoral Fellowship Award 828142.