Melatonin Role and Circadian Rhythms in Children with OSAS

Melatonin is produced by pineal gland. Light inhibits its secretion. Hence, a rhythmical secretion pattern is seen in all species, including humans. In humans, the highest melatonin levels are found in 2- to 5-year-old children; from that age, secretion decrease progressively (Waldhauser, Weiszenbacher, and Tatzer 1988). It has long been known that melatonin has sleep-promoting properties and regulates the sleep-wake cycle. Melatonin has a strong circadian rhythm with high values during the nighttime and low values in the afternoon. Sleep disorders impair the quality of life for children with neurodevelopmental disabilities and their families. Melatonin, a natural regulator of sleep, may be an effective therapy in this area (Wassmer and Whitehouse 2006).

Sleep a disordered breathing may change the circadian rhythms of melatonin, which may have diagnostic implications. One major feature in patients with OSAS is EDS chiefly resulting from disturbed sleep at night. It has been shown that treatment with continuous positive airway pressure (CPAP) may neutralize OSAS completely and abolish the sleep disturbance. Wikner, Svanborg, Wetterberg, and Rojdmark (1997) reported similar nocturnal melatonin levels in patients with OSAS and healthy controls. Sleep apnea recordings were normalized during CPAP treatment and daytime sleepiness disappeared in all patients, neither melatonin secretion nor urinary excretion changed significantly as a result of the CPAP treatment.

Ulfberg, Micic, and Str0m (1998), in another study, showed that in comparison with normal controls, patients suffering from OSAS had significantly higher serum-melatonin levels in the afternoon. However, determination of afternoon serum-melatonin, as a diagnostic test for OSAS in patients with sleep-disordered breathing, showed a low sensitivity but high specificity. Determination of afternoon serum-melatonin alone or together with a scoring of daytime sleepiness does not identify OSAS patients in a heterogeneous population of patients complaining of heavy snoring and EDS (Ulfberg et al. 1998). OSAS in children differs significantly from that in adults. EDS and snoring with apnea are essential diagnostic elements for OSAS in adults, EDS appears to be uncommon in children with equally severe OSAS. Children with OSAS, during the day, can present hyperactivity, decreased intellectual performance and learning problems. We studied circadian rhythms of melatonin in children with severe OSAS. Serum melatonin concentrations were determined every second hour between 8.00 p.m. and 8.00 a.m. during a 12 channels polisomnography. Melatonin secretion among OSAS pediatric patients did not differ from that found in healthy controls. We did not found significant correlation between melatonin circadian secretion, age, or BMI. Only pediatric patients with many body movements during the night presented a significant increment of melatonin secretion (Nosetti et al. 2006) (Fig. 16.1).

Night trend of melatonin mean values - OSAS\control subjects

Night trend of melatonin mean values - OSAS\control subjects

Controls

Hours

02 04

Hours

Figure 16.1. Comparison of the night trend of melatonin (pg/ml) between OSAS patients and control subjects.

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