Sex differences in nocturnal growth hormone and prolactin secretion in healthy older adults: relationships with sleep EEG variables.
OBJECTIVE
To examine sex differences in nocturnal growth hormone and prolactin release in older adults.


METHODS
Sleep was polygraphically recorded for 2 consecutive nights, and blood was sampled at frequent intervals during the last 24 hours.


METHODS
The University of Chicago Clinical Research Center.


METHODS
Two groups of healthy nonobese older subjects: 10 men (59 +/- 2 years, mean +/- SEM), and 10 postmenopausal women (63 +/- 2 years).


METHODS
N/A.


RESULTS
A spectral analysis of the electroencephalogram was performed in the delta and alpha bands. When delta activity was normalized for the activity in rapid eye movement sleep, women had lower delta activity than men. Growth hormone secretion was estimated by deconvolution. The prolactin profile was quantified by a best-fit curve. In both sexes, growth hormone was released both before and after sleep onset. In men, there was no relationship between presleep growth hormone release and subsequent sleep quality and postsleep growth hormone release correlated with delta activity. In women, presleep growth hormone release appeared to inhibit both postsleep growth hormone release and sleep consolidation. Prolactin release was related to rapid eye movement sleep and was lower in men than in women. Women with poor sleep maintenance had a lower prolactin acrophase.


CONCLUSIONS
Major sex differences in the nocturnal profiles of growth hormone and prolactin and their relationship to sleep electroencephalogram variables are present in healthy older adults. Our analyses suggest that lower sleep-onset release of growth hormone in women as compared with men could be related to lower levels of delta activity. Improvements in the homeostatic control of sleep could have hormonal benefits in older adults.
Latta
Federica
F
Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
Leproult
Rachel
R
Tasali
Esra
E
Hofmann
Elisa
E
L'Hermite-Balériaux
Mireille
M
Copinschi
Georges
G
Van Cauter
Eve
E
D000368:Aged; D002940:Circadian Rhythm / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006304:Health Status; D019382:Human Growth Hormone / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011388:Prolactin / Q000378:metabolism*; D012737:Sex Factors; D012890:Sleep / Q000502:physiology*
D019382:Human Growth Hormone; D011388:Prolactin