Introduction: A single night in-lab polysomnography is still the standard method for obstructive sleep apnea (OSA) diagnosis. Recent studies showed considerable internight variability in OSA severity that may affect OSA diagnosis accuracy and treatment decision.

Objectives: Taking benefit of multiple night recordings at home using mandibular jaw movement automated analysis, this study aimed to investigate the interrelationship among various sleep parameters that impact short-term variability of the apnea-hypopnea index (VAHI).

Methods: 160 adults suspected of having OSA completed 3 home sleep tests with the Sunrise device (Sunrise, BE). Data analysis implied generalized estimating equation regression.

Results: After being adjusted for the effect of total sleep time and time interval between nights, regression models showed an internight AHI change of 1.0 e/h (0.4 to 1.5) for each 10% increase in sleep time with head in supine position. An internight AHI decrease of 0.3 e/h (0.2 to 0.4) per % of increase in deep NREM sleep proportion was observed. Results were statistically significant (p<0.001). Therapeutic decision based on a single test would have been different to the decision based on the AHI obtained by averaging the AHI score from the 3 nights in 19.6% of observations.

Conclusions: At the individual level, short-term internight AHI variability is significantly associated with time spent in NREM sleep and with head in supine position. Clinical decision based on a single-night test may lead to misevaluation of OSA severity with wrong therapeutic decisions.