PMC

Mean (± sem) 24-h profiles of norepinephrine (A), epinephrine (B), cortisol (C), and leptin (D) before and after 8 wk of CPAP treatment. Gray bars indicate identical carbohydrate-rich meals (served at 1400, 1900, and 0900 h.) Black bars indicate time in bed. Leptin profiles before and after CPAP are expressed as the percentage of mean 24-h values before CPAP in each individual.

A, Fitted regression values of the change in insulin sensitivity after CPAP as a function of BMI and hours of CPAP use. The dark line represents the line of fit, and dotted lines represent the 95% confidence bands. Improvement in insulin sensitivity after CPAP was greatest among women with a lower BMI (β-coefficient = −1.068; adjusted P = 0.003) and was greater with more hours of CPAP use (β-coefficient = 7.132; adjusted P = 0.027). B, Modeled change in insulin sensitivity expected after 4, 6, and 8 h of CPAP use per night in an overweight patient with a baseline BMI of 28 kg/m² and in an obese patient with a baseline BMI of 35 kg/m². Predicted improvement in insulin sensitivity after treatment of OSA is more pronounced with longer hours of CPAP use in a dose-dependent manner and is of lesser magnitude in patients with higher degrees of obesity.

A, Mean (± sem) daytime (from 1400–2100 and from 0900–1400) profiles of systolic and diastolic blood pressure before and after 8 wk of CPAP treatment. The profiles are illustrated as smoothed data using a three-point moving average (i.e. a window width of 1 h). Mean daytime diastolic blood pressure decreased on average by 2.3 mm Hg after CPAP, whereas there was no significant change in mean daytime systolic blood pressure. B, Mean (± sem) daytime profiles of cardiac autonomic activity derived from HRV analysis of ECG recordings that were obtained during the hour preceding each meal (dinner, breakfast, and lunch) and before bedtime (between 2130 and 2200 h) during the 24-h blood sampling period. HFn is the normalized spectral power in the HF (0.15–0.40 Hz; used as a marker of vagal activity), and LFn is the normalized spectral power in the LF (0.04–0.14 Hz; used as a marker of sympathetic activity). LF to HF ratio (LF/HF; a marker of cardiac sympathovagal balance) was 44% lower after CPAP treatment, reflecting a shift toward lower sympathetic and higher parasympathetic activity.