Sleep Laboratory, Bruce. Rappaport Faculty of. Medicine, Technion-. Israel Institute of. Technology, Haifa, Israel. I Haimov, doctoral student. A Shlitner, senior ...
Sleep disorders and melatonin rhythms in elderly people I Haimov, M Laudon, N Zisapel, M Souroujon, D Nof, A Shlitner, P Herer, 0 Tzischinsky, P Lavie Sleep Laboratory, Bruce Rappaport Faculty of Medicine, TechnionIsrael Institute of Technology, Haifa, Israel I Haimov, doctoral student A Shlitner, senior research assistant P Herer, statistician 0 Tzischinsky, doctoral student P Lavie, professor of behavioural biology
Biological aging is often associated with problems with sleep and daytime napping.' There is considerable evidence linking melatonin, produced by the pineal gland, with the sleep-wake cycle. When administered orally to humans or animals it enhances sleep2 and has a synchronising effect on circadian rhythms. Circulating melatonin concentrations decrease in old age, and its time of secretion is delayed.3 We examined whether sleep disorders in old age were associated with changes in concentration of 6-sulphatoxymelatonin, the major urinary measure ofmelatonin.
Neurim Pharmaceuticals Ltd, Tel Aviv, Israel M Laudon, director of research and development
Patients, methods, and results The study population comprised four groups: (a) eight independently living patients with insomnia (four men, four women, mean age 73 1 (SD 3-9)); (b) 15 patients with insomnia (five men, 10 women, mean age 82-1 (8&8)) who had lived a minimum of six months in a nursing home; (c) 25 elderly patients without sleep disorders (19 men, six women, mean age 71 4 (5 2)) who were living independently in the community; and (d) 12 young men (mean age 24-0 (1 6)) without sleep disorders. None suffered from sleep apnoea, dementia, or depression or were taking any soporific drugs. Subjects' sleep was continuously monitored for one week by miniature actigraphs worn on the wrist. This device translates wrist movements into an electrical signal. Recordings were analysed to determine duration of sleep (total number of minutes defined as sleep), sleep efficiency index (sleep duration as a percentage of total time in bed), and mean activity level (the mean level of actigraphic recording throughout sleep).4 These measures were averaged across all available nights for each subject. Urine was collected approximately every two hours for 24 or 38 hours on the days following the week of actigraphic recording, and 6-sulphatoxymelatonin was assayed in duplicate.5 The interassays and intra-assay coefficients of variation were 7% and 5% respectively. We determined the time of onset of the nocturnal rise in 6-sulphatoxymelatonin excretion, the peak value, and the time of the peak. Two tailed t test analysis showed a significant difference in sleep efficiency and activity level between elderly patients without sleep disorders and those with insomnia (t=4-32, P
