Circadian Melatonin Secretion In Obese Adolescents With Or Without Obstructive Sleep Apnea

Abstract

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.

Circadian Rhythm of Salivary Cortisol in Obese Adolescents With and Without Apnea: A Pilot Study

“…One day prior to PSG, after the adolescents were enrolled in the study, saliva samples for measuring cortisol levels were collected from each participant four times over a 24-h period, namely, at 7:00 h (within 30 min of waking up), 13:00, 19:00, and 23:00 h [the author's technique for saliva collection was developed and applied by Madaeva et al ( 23 ) and tested on adolescents ( 9 )]. A sampling of saliva (4–5 ml) collected within 30 min after eating was avoided, and adolescents were told not to eat or drink milk products or sugary foods on the day of collection.…”

“…Urinary measurements cannot reflect rapid diurnal changes in cortisol levels, and serial urinary sampling may be inconvenient for patients. In contrast, salivary sampling is a non-invasive and easy method that is more comfortable for patients and suitable for the measurement of diurnal cortisol (and some other biomarkers) in children and adolescents ( 8 , 9 ).…”

Circadian Biology in Obstructive Sleep Apnea

“…Therefore, changes in melatonin levels have also been evaluated to better understand changes in circadian biology in patients with OSA. Although, melatonin secretion is rhythmic in OSA patients [73] and may vary among patients with and without OSA [74], a significant number of studies have shown no changes in the rhythmic patterns of melatonin secretion/excretion or in response to dim-light onset among those with OSA compared to healthy controls [69,[75][76][77]. These studies suggest that hormones such as melatonin and cortisol are not preferable as circadian markers for the diagnosis and treatment of OSA.…”