Breathlessness, but not breathing instability, varies with posttraumatic stress symptoms in university students.

Obstructive sleep apnea (OSA) is a chronic sleep-related breathing disorder that is highly prevalent in individuals with posttraumatic stress disorder (PTSD). The reason for this high prevalence remains unclear. We hypothesized that breathing instability, one of the key contributors to OSA, may be altered in PTSD and predispose OSA. Healthy participants (214 females, 98 males) aged 17 to 42 (M = 19.92; SD = 2.85) completed online questionnaires measuring PTSD symptomatology, sleep disturbances, and self-reported breathlessness. A subset of these participants (16 females, 14 males) aged 18 to 42 (M = 23.50; SD = 7.18) completed an in-lab breathing instability assessment, whereby they performed a series of 20-second and maximal duration breath-holds. PTSD severity positively predicted subjective perceptions of breathlessness (P < 0.001) but not objective measures of breathing instability, namely ventilation following 20-s breath-holds (P = 0.93) and maximal breath-hold duration (P = 0.41). These results suggest that breathing instability may not be the driving factor behind the high prevalence of OSA in PTSD. Instead, other factors such as a low arousal threshold, elevated ventilatory responses to arousal, or coexisting insomnia may explain the high rates of OSA in PTSD. One explanation for the discrepancy between subjective breathlessness and breathing stability measures relating to PTSD severity may be that hypervigilance and increased anxiety impacted self-perceptions of breathlessness while not altering breathing instability per se.NEW & NOTEWORTHY Obstructive sleep apnea (OSA) is more common in individuals with posttraumatic stress disorder (PTSD) than the general population for unknown reasons. This study assessed one of the key contributors to OSA, respiratory control instability, in young students with a range of posttraumatic stress symptoms. Although individuals with high PTSD symptoms reported increased subjective breathlessness, objectively measured breathing instability was not altered, suggesting respiratory instability is unlikely to increase the risk of OSA in PTSD.