Partial and largely conflicting data are currently available on the interplay between obstructive sleep apnea (OSA) and hypothalamus-pituitary-adrenal axis (HPA) activity in adult obese men. This study was performed to evaluate the daily trajectories of salivary cortisol, specifically with respect to the salivary cortisol awakening response (CAR), a common method used to assess HPA axis activity. The main findings of this study were that adult male obese subjects who were newly diagnosed with severe OSA showed the following: (1) a flattening of the CAR; (2) levels of cortisol at awakening that were lower than those of the controls; and (3) maintenance of the physiological circadian activity of the HPA axis, with the highest hormone concentrations produced in the morning and the lowest in the evening. This study was also designed to investigate the effects of 3 and 6 mos of treatment with continuous airways positive pressure (CPAP). CPAP use resulted in a significant recovery of the sleep patterns disrupted by OSA; moreover, mild neuropsychological signs of depression and anxiety in severe OSA patients were concomitantly progressively improved by CPAP treatment. Furthermore, this study reports that 3 and 6 mos of CPAP therapy restored the presence of CAR and was able to significantly reduce the difference in the morning cortisol levels between the OSA and control groups. In conclusion, we report here that compared with obese nonapneic matched controls, OSA patients present a dysregulation of HPA axis activity, as shown by the flattening of the diurnal pattern of cortisol production in response to repeated challenge due to hypoxia and sleep fragmentation. This dysregulation was especially detectable in the first hour after awakening and restored after 3 and 6 mos of treatment with CPAP.

OSA-related fatigue was strongly associated with serum testosterone, together with OSA severity.

The main finding was that OSA subjects displayed hypocortisolism upon awakening and a significant reduction in testosterone concentration in the evening in comparison with the control group, which has maintained the physiological testosterone and cortisol diurnal fluctuation, with higher hormone concentrations in the morning and lower concentrations in the evening. The use of data from multiple diurnal measurements rather than a single point allowed the detection of T/C ratio changes of opposite signs at the beginning and end of the day: the OSA subjects had a higher T/C ratio than the controls in the morning, while their T/C ratio was significantly lower than that of the controls in the evening. The imbalances in the anabolic-catabolic diurnal equilibrium suggest that OSA is associated with a dysregulation of the hypothalamic-pituitary-adrenal and hypothalamic-pituitary-gonadal axes, potentially an underlying cause of some of the neuropsychological comorbidities observed in OSA patients.

BackgroundObstructive sleep apnea-hypopnea syndrome (OSAHS) is characterized by repeated breathing pauses during sleep and is closely associated with obesity. Body fat is known to be a predictive factor for OSAHS and its severity.AimTo study the correlation between the severity of OSAHS and body composition measurements.Methods30 patients with OSAHS (21 men, 9 women, mean age 45.1 years, mean apnea-hypopnea index = 29.6/hour) were included in the study after full polysomnography. They were divided into 3 groups according to the apnea-hypopnea index (AHI): mild OSAHS (mean AHI 10.9/h), moderate OSAHS (mean AHI 23.9/h) and severe OSAHS (mean AHI 53.9/h). Body composition (body fat, body water and dry lean mass) was assessed using bioelectric impedance assay (BIA). Other measurements included neck and abdominal circumferences and body mass index (BMI). Pearson's coefficient (r) was used to express correlations between AHI and the following parameters: BMI, neck and abdominal circumferences, body fat, dry lean mass, and body water. Wilcoxon Sum-of-Ranks (Mann-Whitney) test for comparing unmatched samples was used to compare anthropometric and body composition measurements between groups.ResultsThe correlation between AHI and BMI was weak (r = 0.38). AHI correlated moderately with neck circumference (r = 0.54), with neck circumference corrected by height (r = 0.60), and more strongly with body fat (r = 0.67), with body water (r = 0.69) and with abdominal circumference (r = 0.75). There was a strong negative correlation between AHI and dry lean mass (r = - 0.92). There were significant differences in body fat, body water, neck circumference corrected by height and abdominal circumference (Wilcoxon Sum-of-Ranks, p < 0.01), between mild and severe OSASH groups, but not in BMI (Wilcoxon Sumof-Ranks, W = 86.5; p = 0.17).ConclusionsIn our study, the severity of OSAHS correlated with body fat and with body water more strongly than with general and cervical obesity. Abdominal adiposity may predict OSAHS severity better than neck circumference.

Obstructive sleep apnoea (OSA), also characterised by hypoxia-related sleep- fragmentation, has been studied in relation to depression and serum testosterone deficit. In middle-aged men, it has been reported the association between depressive mood and low serum testosterone level; however, no data are available about this association in OSA patients. Therefore, the aim of this study was to investigate in adult obese males, affected by severe OSA, the relationship between serum testosterone concentration and depressive symptoms, in order to identify among all measured parameters (serum testosterone morning concentration, polysomnography parameters, body mass index, Epworth Sleepiness Scale) those predictors for OSA-related depression. Forty patients diagnosed with severe OSA and forty subjects for the control-matched group were enroled in the study. The results indicated that the serum testosterone in OSA group was significantly lower than in controls. In addition, the OSA group presented a level of depression although moderate, yet significantly higher than controls. Furthermore, a statistically significant inverse correlation has been found between serum testosterone level and depressive symptoms. Among all variables, serum testosterone level was shown to be the only independent variable significantly predictor for depression in OSA patients.