title: Melatonin effects on luteinizing hormone in postmenopausal women: a pilot clinical trial NCT00288262.
abstract: BACKGROUND
  In many mammals, the duration of the nocturnal melatonin elevation regulates seasonal changes in reproductive hormones such as luteinizing hormone (LH). Melatonin's effects on human reproductive endocrinology are uncertain. It is thought that the same hypothalamic pulse generator may both trigger the pulsatile release of GnRH and LH and also cause hot flashes. Thus, if melatonin suppressed this pulse generator in postmenopausal women, it might moderate hot flashes. This clinical trial tested the hypothesis that melatonin could suppress LH and relieve hot flashes.
  
  
  METHODS
  Twenty postmenopausal women troubled by hot flashes underwent one week of baseline observation followed by 4 weeks of a randomized controlled trial of melatonin or matched placebo. The three randomized treatments were melatonin 0.5 mg 2.5-3 hours before bedtime, melatonin 0.5 mg upon morning awakening, or placebo capsules. Twelve of the women were admitted to the GCRC at baseline and at the end of randomized treatment for 24-hour sampling of blood for LH. Morning urine samples were collected twice weekly to measure LH excretion. Subjective responses measured throughout baseline and treatment included sleep and hot flash logs, the CESD and QIDS depression self-ratings, and the SAFTEE physical symptom inventory.
  
  
  RESULTS
  Urinary LH tended to increase from baseline to the end of treatment. Contrasts among the 3 randomized groups were statistically marginal, but there was relative suppression combining the groups given melatonin as contrasted to the placebo group (p < 0.01 one-tailed, Mann-Whitney U = 14). Similar but not significant results were seen in blood LH. There were no significant contrasts among groups in hot flashes, sleep, depression, or side-effect measures and no significant adverse effects of any sort.
  
  
  CONCLUSIONS
  The data are consistent with the hypothesis that melatonin suppresses LH in postmenopausal women. An effect related to the duration of nocturnal melatonin elevation is suggested. Effects of melatonin on reproductive endocrinology should be studied further in younger women and in men. Larger studies of melatonin effects on postmenopausal symptoms would be worthwhile.
authors.affiliation: Scripps Clinic Sleep Center, 10666 North Torrey Pines Road, La Jolla, California 92037, USA. Kripke.Daniel@ScrippsHealth.org
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Kripke
authors.forename: Lawrence E
authors.initials: LE
authors.lastname: Kline
authors.forename: Farhad F
authors.initials: FF
authors.lastname: Shadan
authors.forename: Arthur
authors.initials: A
authors.lastname: Dawson
authors.forename: J Steven
authors.initials: JS
authors.lastname: Poceta
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Elliott