Respiration-Triggered Olfactory Stimulation ReducesObstructive Sleep Apnea Symptoms Severity: A Prospective Pilot Study
Obstructive sleep apnea (OSA) is a prevalent sleep-disordered breathing condition characterized by repetitive reduction in breathing during sleep. Current care standard for OSA is continuous positive air pressure devices, often suffering from low tolerance due to limited adherence. Capitalizing on the unique neurocircuitry of olfactory perception and its retained function during sleep, we conducted a pilot study to test transient, respiration-based olfactory stimulation as a treatment for OSA markers. Thirty-two OSA patients (Apnea-Hypopnea Index (AHI)[≥]15 events/hour) underwent two polysomnography sessions, Odor and Control, in random order. In Odor nights, patients were presented with transient respiratory-based olfactory stimulation delivered via a computer-controlled commercial olfactometer (Scentific). The olfactometer, equipped with a wireless monitoring, analyzed respiratory patterns and presented odor upon detection of respiratory events. No odors were presented in Control nights. Following exclusions, 17 patients entered analysis (4 women, 47.4 (10.5) years, BMI: 33.8 (7.8)). We observed that olfactory stimulation during sleep reduced AHI ( Odor:17.2 (20.9), Control: 28.2 (18.6), z=- 3.337, p=0.000846, BF10=57.9), reflecting an average decrease of 31.3% in event number. Relatedly, stimulation reduced the oxygen desaturation index (ODI) by 26.9% ( Odor: 12.5 (15.8), Control: 25.7 (25.9), z=-3.337, p=0.000846, BF10=9.522. This effect was not linked to baseline OSA markers severity ({rho}=-0.042, p=0.87). Olfactory stimulation did not arouse from sleep or affect sleep structure, measured as time per sleep stage (F(1,16)=0.088, p=0.77). In conclusion, olfactory stimulation during sleep was effective in reducing OSA markers severity without inducing arousals and may provide a novel treatment for OSA, prompting continued research.