title: Do plasma melatonin concentrations decline with age?
abstract: OBJECTIVE
  Numerous reports that secretion of the putative sleep-promoting hormone melatonin declines with age have led to suggestions that melatonin replacement therapy be used to treat sleep problems in older patients. We sought to reassess whether the endogenous circadian rhythm of plasma melatonin concentration changes with age in healthy drug-free adults.
  
  
  METHODS
  We analyzed the amplitude of plasma melatonin profiles during a constant routine in 34 healthy drug-free older subjects (20 women and 14 men, aged 65 to 81 years) and compared them with 98 healthy drug-free young men (aged 18 to 30 years).
  
  
  RESULTS
  We could detect no significant difference between a healthy and drug-free group of older men and women as compared to one of young men in the endogenous circadian amplitude of the plasma melatonin rhythm, as described by mean 24-hour average melatonin concentration (70 pmol/liter vs 73 pmol/liter, P = 0.97), or the duration (9.3 hours vs 9.1 hours, P = 0.43), mean (162 pmol/liter vs 161 pmol/liter, P = 0.63), or integrated area (85,800 pmol x min/liter vs 86,700 pmol x min/liter, P = 0.66) of the nocturnal peak of plasma melatonin.
  
  
  CONCLUSIONS
  These results do not support the hypothesis that reduction of plasma melatonin concentration is a general characteristic of healthy aging. Should melatonin replacement therapy or melatonin supplementation prove to be clinically useful, we recommend that an assessment of endogenous melatonin be carried out before such treatment is used in older patients.
authors.affiliation: Department of Medicine, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Zeitzer
authors.forename: J E
authors.initials: JE
authors.lastname: Daniels
authors.forename: J F
authors.initials: JF
authors.lastname: Duffy
authors.forename: E B
authors.initials: EB
authors.lastname: Klerman
authors.forename: T L
authors.initials: TL
authors.lastname: Shanahan
authors.forename: D J
authors.initials: DJ
authors.lastname: Dijk
authors.forename: C A
authors.initials: CA
authors.lastname: Czeisler
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood*; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D008297:Male; D008550:Melatonin / Q000097:blood*; D012893:Sleep Wake Disorders / Q000097:blood / Q000188:drug therapy / Q000209:etiology*
chemical_list: D008550:Melatonin