Independent association between hypoxemia and night sweats in obstructive sleep apnea

To assess the relationship between hypoxemia during polysomnography (PSG) and patient-reported night sweats (NS).

This retrospective observational study included adult patients who completed a standardized sleep questionnaire and the Epworth Sleepiness Scale (ESS) before PSG.

We included 1397 patients (41% women). The median age was 52 years, 80% had obstructive sleep apnea (OSA) defined as an apnea-hypopnea index (AHI) ≥ 5, and 35% were obese. A total of 245 patients (17.5%) reported NS. Their prevalence was higher among patients with OSA compared to controls (18.9% vs. 12.2%, p < 0.01). In the bivariate analysis, the variables associated with NS were BMI, AHI, hypoxemia (T90 ≥ 2.5% of total recording time plus minimum SO₂ < 85%), frequent body movements or awakenings, nightmares, excessive daytime sleepiness (Epworth > 10), nocturia, cardiovascular events, and the use of sedatives or antidepressants. In the multivariate model, the independent predictors of NS were BMI (OR: 1.47, CI 95%: 1.07-2.01, p = 0.016), hypoxemia (OR: 1.87, CI 95%: 1.37-2.60, p = 0.0001), nightmares (OR: 2.60, CI 95%: 1.73-3.80, p < 0.0001), frequent body movements and awakenings (OR: 1.57, CI 95%: 1.16-2.11, p = 0.003 and OR: 1.54, CI 95%: 1.13-2.08, p = 0.005, respectively), and excessive daytime sleepiness (OR: 1.65, CI 95%: 1.24-2.20, p = 0.0007).

In patients with OSA, night sweats were significantly and independently associated with a higher hypoxic burden.