K. Lushington et al., DAYTIME MELATONIN ADMINISTRATION IN ELDERLY GOOD AND POOR SLEEPERS - EFFECTS ON CORE BODY-TEMPERATURE AND SLEEP LATENCY, Sleep, 20(12), 1997, pp. 1135-1144
Melatonin has been shown to have hypnotic and hypothermic effects in y
oung adults and has been proposed as treatment for insomnia. However,
the hypnotic and thermoregulatory effects of melatonin remain to be si
multaneously investigated for aged good and poor sleepers. The aim of
this study was to explore the short term effects of exogenous oral day
time melatonin on core body temperature, sleep latency, and subjective
vigor and affect in aged women. Twelve sleep maintenance insomniacs a
nd 10 good sleeping postmenopausal female subjects [mean (SD) age = 65
.2 (7.4) years] participated in a double-blind, crossover study in whi
ch they received a capsule containing either melatonin (5 mg) or a pla
cebo at 1400 hours. Continuous core body temperature and hourly multip
le sleep latency tests (MSLT) were collected from 1100-2030 hours. Sel
f-reported estimates of global vigor (sleepiness) and affect were coll
ected prior to each MSLT using visual analog scales. Comparison of goo
d and poor sleepers failed to reveal any significant differences in co
re body temperature, sleep latency, or subjective vigor and affect. Ho
wever, for both groups combined, melatonin administration [absolute po
stadministration mean (SEM) = 36.9 (0.05)degrees C] significantly lowe
red core body temperature compared with placebo [37.1 (0.05)degrees C]
. Similarly, melatonin administration significantly reduced latency to
stage 1 (SOL1) and stage 2 (SOL2) [absolute postadministration mean S
OL1 = 20.1 (1.7) and SOL2 = 20.7 (1.6) minutes] compared with placebo
[SOL1 = 24.3 (1.2) and SOL2 = 25.2 (1.1) minutes]. Treatment had no si
gnificant effect on either vigor or affect. Overall, our results sugge
st that although short-term exogenous oral daytime melatonin has signi
ficant hypothermic and hypnotic effects in aged women, the size of the
effects is modest.