Objective — To compare melatonin levels in saliva during a 24-hr day in order to identify the specificities of circadian melatonin secretion in obese adolescents with or without obstructive sleep apnea (OSA). Material and Methods — We examined 18 obese adolescents with OSA, 12 obese adolescents without OSA, and 15 healthy adolescents with a normal body weight, from whom saliva was sampled four time during the 24-hr day. Polysomnography was used to diagnose OSA. Saliva samples (n=180) were subjected to enzyme-linked immunosorbent assay. Results — Obese adolescents with OSA had higher evening melatonin levels than obese adolescents without OSA. For example, this indicator in OSA patients was 5.3 times higher than in participants without OSA, who had the lowest evening melatonin level among all groups. In both obese groups, nighttime melatonin levels were significantly lower than in the control group. A positive correlation was detected between the levels of morning and afternoon melatonin and body mass index only in obese adolescents without OSA (r=0.58; p=0.03 and r=0.68; p=0.01, respectively). It was found that evening melatonin correlated with minimum blood oxygen saturation (SaO2) in the entire sample of adolescents with OSA (r=-0.69; p=0.008), and it also correlated with time with SaO2 <90% in the group with clinical manifestations of OSA (r=0.76; p=0.003). Nighttime melatonin levels negatively correlated with the minimum SaO2 value solely in the group with clinical manifestations of OSA (r=-0.58; p=0.035). Conclusion — The circadian melatonin secretion in obese adolescents differed, depending on the presence or absence of OSA, and correlated with the level of oxygen desaturation in OSA patients, to a greater extent – in the presence of clinical manifestations.

Background: Inadequate sleep duration and sleep patterns have been associated with metabolic and circadian changes that promote obesity. The aim of this study was to applicate a translated version of the Adolescent Sleep Habits Survey to assess sleep habits and schedules in Russian obese adolescents.Methods and Results: We questioned 87 adolescents aged between 15 and 17 years: 57 with obesity and 30 with a normal weight (NW). In total, some sleep problems were observed in 60.8% of obese respondents and 28.6% of NW participants (P=0.048). School-night wake times in obese adolescents did not differ significantly from the same variables in NW adolescents. School-night bedtimes and TST only in an obese sample were later and shorter, respectively, than in NW subjects (P<0.001 for both variables). Surprisingly, NW adolescents had a greater bedtime shift than obese peers (P<0.001). Finally, about half of obese respondents reported that they usually eat (62.7%) and watch TV (44.4%) in bed (P<0.001 for both variables compared with controls).Conclusions: Applying a translated version of ASHS helps assess sleep habits and schedules in Russian adolescents, including obese patients.