[Rhythm of melatonin excretion in obstructive sleep apnea syndrome]

Melatonin is a pineal hormone that regulates sleep and wake status. Melatonin concentrations in blood serum were measured using radioisotope method in 33 males (age 48 +/- 10) with obstructive sleep apnea syndrome. The following melatonin concentrations were measured: 54 +/- 72 pg/ml (9 p.m.) 424 +/- 838 pg/ml (2 a.m.) and 307 +/- 534 pg/ml (6 a.m.). In patients with high peak melatonin concentration (> 200 pg/ml) as compared with the patients with low peak melatonin concentration (< 200 pg/ml) there were higher index of respiratory disorders during sleep (53 +/- 18 vs 38 +/- 20, p < 0.05) and lower minimal SaO2 during sleep apnea (52 +/- 17% vs 70 +/- 10%, p < 0.05); they were also more tired in the morning and were more sleepy during the day (Epworth sleepiness scale 17 +/- 6 vs 11 +/- 6, p < 0.01). In 66% of patients peak melatonin concentration was observed at 2 a.m. In 24% of patients peak melatonin secretion was prolonged to early morning hours.

In most of patients there is peak melatonin excretion at 2 a.m. Patients with high apnea and hypopnea index and daytime sleepiness have high peak melatonin concentrations.