{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,7]],"date-time":"2026-02-07T22:51:27Z","timestamp":1770504687834,"version":"3.49.0"},"reference-count":33,"publisher":"SAGE Publications","issue":"5","license":[{"start":{"date-parts":[[2003,10,1]],"date-time":"2003-10-01T00:00:00Z","timestamp":1064966400000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J Biol Rhythms"],"published-print":{"date-parts":[[2003,10]]},"abstract":"<jats:p> Exogenous melatonin (0.5-10 mg) has been shown to entrain the free-running circadian rhythms of some blind subjects. The aim of this study was to assess further the entraining effects of a daily dose of 0.5 mg melatonin on the cortisol rhythm and its acute effects on subjective sleep in blind subjects with free-running 6-sulphatoxymelatonin (aMT6s) rhythms (circadian period [\u03c4] 24.23-24.95 h). Ten subjects (9 males) were studied, aged 32 to 65 years, with no conscious light perception (NPL). In a placebo-controlled, single-blind design, subjects received 0.5 mg melatonin or placebo p.o. daily at 2100 h (treatment duration 26-81 days depending on individuals' circadian period). Subjective sleep was assessed from daily sleep and nap diaries. Urinary cortisol and aMT6s were assessed for 24 to 48 h weekly and measured by radioimmunoassay. Seven subjects exhibited an entrained or shortened cortisol period during melatonin treatment. Of these, 4 subjects entrained with a period indistinguishable from 24 h, 2 subjects continued to run for up to 25 days during melatonin treatment before their cortisol rhythm became entrained, and 1 subject appeared to exhibit a shortened cortisol period throughout melatonin treatment. The subjects who entrained within 7 days did so when melatonin treatment commenced in the phase advance portion of the melatonin PRC (CT6-18). When melatonin treatment ceased, cortisol and aMT6s rhythms free ran at a similar period to before treatment. Three subjects failed to entrain with initial melatonin treatment commencing in the phase delay portion of the PRC. During melatonin treatment, there was a of free significant increase in nighttime sleep duration and a reduction in the number and duration of daytime naps. The positive effect of melatonin on sleep may be partly due to its acute soporific properties. The findings demonstrate that a daily dose of 0.5 mg melatonin is effective at entraining the free-running circa-dian systems in most of the blind subjects studied, and that circadian time (CT) of administration Optimal melatonin may be important entrains to melatonin treatment. 24-h sleep disorder should p.o. in determining whether a subject disorder the sleep-wake cycle) in addition to improving sleep acutely. correct treatment with melatonin for the underlying circadian this (to non-entrain <\/jats:p>","DOI":"10.1177\/0748730403256796","type":"journal-article","created":{"date-parts":[[2003,10,2]],"date-time":"2003-10-02T20:35:05Z","timestamp":1065126905000},"page":"420-429","source":"Crossref","is-referenced-by-count":143,"title":["The Effects of Low-Dose 0.5-mg Melatonin on the Free-Running Circadian Rhythms of Blind Subjects"],"prefix":"10.1177","volume":"18","author":[{"given":"Lisa M.","family":"Hack","sequence":"first","affiliation":[{"name":"Centre for Chronobiology, School of Biomedical and Life Sciences, University of Surrey, Guildford, GU2 7XH, UK"}]},{"given":"Steven W.","family":"Lockley","sequence":"additional","affiliation":[{"name":"Centre for Chronobiology, School of Biomedical and Life Sciences, University of Surrey, Guildford, GU2 7XH, UK"}]},{"given":"Josephine","family":"Arendt","sequence":"additional","affiliation":[{"name":"Centre for Chronobiology, School of Biomedical and Life Sciences, University of Surrey, Guildford, GU2 7XH, UK"}]},{"given":"Debra J.","family":"Skene","sequence":"additional","affiliation":[{"name":"Centre for Chronobiology, School of Biomedical and Life Sciences, University of Surrey, Guildford, GU2 7XH, UK,"}]}],"member":"179","published-online":{"date-parts":[[2003,10,1]]},"reference":[{"key":"atypb1","doi-asserted-by":"publisher","DOI":"10.1177\/000456328802500319"},{"key":"atypb2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1365-2125.1985.tb02679.x"},{"key":"atypb3","doi-asserted-by":"crossref","unstructured":"Arendt J, Aldhous ME, and Wright J (1988) Synchronisation of a disturbed sleep-wake cycle in a blind man by melatonin treatment. 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