Circadian rhythms of melatonin, cortisol and cytokines in pediatric obstructive sleep apnea syndrome

Introduction: Several neuroimmunological mediators exhibit a circadian organization. Melatonin, cortisol and somnogenic cytokines can be altered in conditions of disturbed sleep. Aims and objectives: The aim of the research is to investigate whether melatonin, cortisol, Tumor Necrosis Factor-α (TNF-α) and Interleukin-1β (IL-1β) show altered circadian rhythms in pediatric Obstructive Sleep Apnea (OSAS). Methods: 47 children (26 OSAS, 21 not OSAS) underwent a nocturnal polysomnography and 2 blood samples were taken (2.00 am and 8.00 am). Cortisol and melatonin plasma concentrations were assayed using a radioimmunoassay technique. Cytokines were dosed from the supernatant of a 24-hours cell culture system (ELISA) in basal condition and after stimulation with phytohemagglutinin (PHA). Results: The circadian organization of cortisol and melatonin was not altered in OSAS. In fact pediatric OSAS is not associated with an important sleep fragmentation that could affect circadian rhythms of hormones. Circadian rhythms of TNF-α and IL-1β had lost the nocturnal physiological peak and an additional early morning peak had developed (TNF-α: P Conclusions: The interaction among sleep regulation, circadian rhythms, inflammation, immunomodulation and hormone release is an interesting starting point for future research in this field.