Physiological melatonin levels in healthy older people: A systematic review.
Melatonin plays a major role in maintaining circadian rhythm. Previous studies showed that its secretion pattern and levels could be disturbed in persons with dementia, psychiatric disorders, sleep disorders or with cancer. Also ageing is a factor that could alter melatonin levels, although previous research provides contradicting results. As melatonin supplementation is increasingly applied in older persons as sleep medication, it is important to know if melatonin levels decrease in healthy ageing and/or secretion patterns change. The objective of this study is to determine physiological levels and secretion patterns of melatonin in healthy older people.



We performed a systematic review and searched PubMed and Embase for studies published between January 1st 1980 and October 5th 2015 that measured melatonin in healthy persons aged ≥65years.



Nineteen studies were retrieved. The number of participants ranged from 5 to 60 per study. Melatonin was mostly measured by radioimmunoassay (RIA) and the number of measurements per 24hours varied from 1 to 96. Sixteen studies showed a secretion pattern with a clear peak concentration, mostly at 0200h or 0300h. Maximum concentrations varied greatly from 11.2 to 91.3pgml(-1). Maximum melatonin level in studies with participants mean aged 65-70years was 49.3pgml(-1) and in studies with participants mean aged ≥75years 27.8pgml(-1), p-value <0.001.



Total melatonin production in 24hours seems not to change in healthy ageing, but the maximal nocturnal peak concentration of melatonin might decline. It is important to take this into account when prescribing melatonin supplementation to older people.
Academic Medical Center, University of Amsterdam, Department of Internal Medicine, Geriatrics section, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. Electronic address: r.m.scholtens@amc.uva.nl.
Rikie M
RM
Scholtens
Academic Medical Center, University of Amsterdam, Department of Internal Medicine, Geriatrics section, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; Gelre Hospitals, Department of Geriatrics, Albert Schweitzerlaan 31, 7334 DZ Apeldoorn, The Netherlands.
Barbara C
BC
van Munster
Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
Marijn F
MF
van Kempen
Academic Medical Center, University of Amsterdam, Department of Internal Medicine, Geriatrics section, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; University Medical Center Groningen, University Centre for Geriatric Medicine, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.
Sophia E J A
SE
de Rooij
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood* / Q000523:psychology; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology; D003704:Dementia / Q000097:blood / Q000188:drug therapy / Q000523:psychology; D019587:Dietary Supplements; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008550:Melatonin / Q000008:administration & dosage* / Q000097:blood* / Q000502:physiology; D064887:Observational Studies as Topic / Q000379:methods; D012890:Sleep / Q000187:drug effects / Q000502:physiology; D012893:Sleep Wake Disorders / Q000097:blood / Q000188:drug therapy / Q000523:psychology
D008550:Melatonin
Aged; Ageing; Circadian rhythm; Elderly; Melatonin; Pineal gland