Sleeping disorders related with alterations of melatonine secretion circadian rhythm

Abstract

Introduction Several circadian rhythms have been used as indicators of the endogenous circadian pacemaker phase, but circadian rhythm of pineal melatonin secretion has been proved to be the indicator that most exactly describes the function of the suprachiasmatic nucleus. Dim Light Melatonin Onset (DLMO) determination is the only marker available of circadian rhythm pacemaker phase. This determination requires 5 blood, saliva or urine samples. DLMO test is a precise tool used to distinguish between sleep disorder patients with or without a subjacent alteration of circadian rhythm. Materials and methods A sample (N = 146) of 6–11 year old patients (65.75% men and 34.25% women) was selected. 730 determinations of salivary melatonin were carried out (5 per subject). Suitable samples were centrifuged 10 min to remove particulate material and frozen at −70°C until analysis. Quantitative determination of melatonin was performed by a direct non-extraction ELISA assay using DSX analyser. DMLO levels for each patient were determined and were then classified as normal o altered. Patients were also subjected to the Paediatric Sleep Questionnaire of Chervin for Sleep disorder diagnosis. Statistical analysis was carried to evaluate the null hypothesis against the alternative hypothesis (H0: DLMO is not related with sleeping disorders; H1: a relation exists between DLMO and sleeping disorders). Results Statistical analysis of DLMO difference between patients with and without sleeping disorders led the following results: Excessive daytime sleepiness (p-value 0.5789), Respiratory disorder related with sleep (p-value 0.8649), Bruxism (p-value 0.5866), Enuresis (p-value 0.0138), sleepwalking (p-value 0.7443), nightmares (p-value 0.4822), night terrors (p-value 0.9695), rhythmic movement disorders (p-value 0.5951), Insomnia (p-value 0.0014), Somniloquy (p-value 0.0178), Arousals (p-value 0.0001), Sleep start delay (p- value 0.0166), Sleep latency (p-value 0.0123), Bed- time resistance (p-value 0.4209), Awakening and Bedtime irregularity (p-value 0.5138). Conclusion The following sleeping disorders proved to have a significant relation with DLMO levels (p 0.05): enuresis, somniloquy, insomnia, arousals, sleep start delay and sleep latency. Acknowledgements Hospital Universitario de la Ribera for the trust placed in researchers and in the present study.