AFTERNOON SERUM-MELATONIN IN SLEEP-DISORDERED BREATHING

Objectives, To study afternoon serum-melatonin values in patients with sleep disordered breathing. Melatonin has a strong circadian rhythm w ith high values during the night-time and low values in the afternoon. Sleep disordered breathing may change the circadian rhythm of melaton in which may have diagnostic implications. Setting. The Sleep Laborato ry, The Department of Internal Medicine, Avesta Hospital, Sweden, and the Department of Anaesthesiology, Glostrup University Hospital, Copen hagen, Denmark. Subjects. We examined 60 consecutive patients admitted for sleep disordered breathing and 10 healthy non snoring controls, T he patients underwent a sleep apnoea screening test having a specifici ty of 100% for the obstructive sleep apnoea syndrome (OSAS) using a co mbination of static charge sensitive bed and oximetry. Obstructive sle ep apnoea syndrome was found in 49 patients, eight patients had border line sleep disordered breathing (BSDB) and three patients were exclude d due to interfering disease. Main outcome measures, Patients and cont rols had an afternoon determination of serum-melatonin. The Epworth Sl eepiness Scale was used to score daytime sleepiness. Results. In compa rison with normal controls patients suffering from OSAS had significan tly higher serum-melatonin levels in the afternoon. However, as a diag nostic test for OSAS in patients with sleep disordered breathing serum -melatonin showed a low sensitivity but a high specificity. The result s indicate that breathing disorders during sleep in general affect pin eal function. Conclusions. Sleep disordered breathing seems to disturb pineal function. Determination of afternoon serum-melatonin alone or together with a scoring of daytime sleepiness does not identify OSAS-p atients in a heterogeneous population of patients complaining of heavy snoring and excessive daytime sleepiness.