Melatonin in Older People with Age-Related Sleep Maintenance Problems: A Comparison with Age Matched Normal Sleepers

STUDY OBJECTIVES: To determine whether older people with age-related sleep maintenance problems have significantly lower melatonin levels than comparable normal sleepers. DESIGN: Case-control study. SETTING: A largely urban population, Auckland, New Zealand. PARTICIPANTS: People over the age of 65 years, who either slept normally, or had age-related sleep maintenance problems. Participants were recruited through media advertising, and local interest groups. Initial screening was by mail (Pittsburgh Sleep Quality Index), followed by interviews at a hospital day clinic. Exclusions included those with depression, cognitive impairment, medical and/or environmental problems which might impair sleep. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: A metabolite of plasma melatonin, 6-sulphatoxymelatonin (aMT6s) was measured in the urine of 57 normal sleepers, and 53 people with age-related problems over 24 hours in three aliquots: 12:00-19:00h, 19:00-07:00h, 07:00-12:00h. There were clear differences in self reported quality of sleep but no difference in mean aMT6s 24 hour or total night excretory levels, or night/day ratios. CONCLUSIONS: Older people with age-related sleep maintenance problems do not have lower melatonin levels than older people reporting normal sleep.