6-Sulfatoxymelatonin excretion and self-reported sleep in good sleeping controls and 55-80-year-old insomniacs

The pineal hormone melatonin is thought to play a role in sleep initiation and maintenance. This was examined in a large sample of good sleeping controls (n = 52) and sleep maintenance insomniacs (n = 56), aged 55-80 y. Subjects collected 5 d of self-reported sleep diary measures, and 12-h urine samples (08.00-20.00 and 20.00-08.00 h) for analysis of the urinary melatonin metabolite, 6-sulphatoxymelatonin (aMT.6S). Insomniacs reported a significantly greater amount of wake after sleep onset, less sleep in total, less efficient sleep and poorer quality sleep compared to controls. However, no significant differences in melatonin excretion were observed between controls and insomniacs, with both groups showing similar mean (SEM) 12-h night-time [30.9 (2.9) vs. 30.6 (3.3) nmoles, respectively] as well as 24-h total [38.7 (3.4) vs. 36.7 (3.8)] aMT.6S excretion levels. No significant correlations were observed with any sleep parameters nor any effects of medication (anti-inflammatory agents, hormone replacement therapy, and an undifferentiated group of medications). The present results do not support a simple relationship between total melatonin production and self-reported sleep quality and duration in the aged.