Melatonin in patients with delayed sleep phase disorder

Abstract

Delayed sleep phase disorder (DSPD) is common mainly in adolescents and young adults and has a complex treatment that involves behavioral techniques, phototherapy and melatonin administration. Therapeutic failures and relapses are frequent. Considering the characteristics of circadian rhythms and the fact that their reactivity to a specific therapy depends on the phase that it is administered, it is essential to determine with accuracy the nadir of temperature rhythm or the initiation of melatonin production – DLMO (dim light melatonin onset). 69 patients aged from 18 to 85 years (41.9 ± 14.8), with DSPD according to AASM 2005 were selected. The measurement of melatonin in saliva samples occurred at 5 consecutive hours (last collection occurred one hour after the usual sleep onset). Melatonin concentration was measured with a radioimmunoassay and DLMO was defined as the time at which the melatonin concentration in saliva reaches 4 pg/ml. All patients underwent polysomnography (PSG) after the saliva collections. DLMO could be determined in 39 patients (56,5%). Failure of DLMO determination was mainly due to profiles with low melatonin values – between 0.5 and 3 pg/mL (26.9%) or profiles where melatonin levels were already above the threshold of 4 pg/mL (17%). In these cases patients may have a wrong perception of sleep onset, or are persistent low melatonin secretors. There were no age differences in the DLMO measurements. The PSG showed a subgroup of patients with poligraphic characteristics of insomnia. DLMO allowed the confirmation of DSPD in 56.5% of patients. It also enabled the identification of patients with behavioral DSPD. Insomnia was present in a patient subgroup.