Neuroendocrine rhythms and sleep in aging men

Abstract

To delineate the physiological effects of aging on basal levels and temporal patterns of neuroendocrine secretions, the 24-h profiles of cortisol, thyroid-stimulating hormone (TSH), melatonin, prolactin, and growth hormone (GH) levels were simultaneously obtained at frequent intervals in eight healthy, active elderly men, age 67-84 yr and in eight young male adults, age 20-27 yr. The study was preceded by an extended period of habituation to laboratory conditions, and sleep was polygraphically recorded. Mean cortisol levels in the elderly were normal, but the amplitude of the circadian rhythm was reduced. Circulating levels of daytime and nighttime levels of both TSH and GH were greatly diminished in old age. In contrast, prolactin and melatonin concentrations were decreased during the nighttime only. The circadian rises of cortisol, TSH, and melatonin occurred 1-1.5 h earlier in elderly subjects, and the distribution of rapid-eye-movement stages during sleep was similarly advanced, suggesting that circadian timekeeping is modified during normal senescence. Despite perturbations of sleep, sleep-related release of GH and prolactin occurred in all elderly men. Age-related decreases in hormonal levels were associated with a decrease in the amplitude, but not the frequency, of secretory pulses. These findings demonstrate that the normal process of aging involves alterations in the central mechanisms controlling the temporal organization of endocrine release in addition to a reduction of secretory outputs.

Long-Term Monitoring and Analysis of Age-Related Changes on Autonomic Nervous Function

“…age-related [28], in this study also there was a trend that suggests a decrease with age in autonomic nervous function while sleeping as one of the causes.…”

Effects of long-term continuous positive airway pressure on body composition and IGF1

“…Several studies have demonstrated a significant relationship between a reduction of slow-wave sleep, decreased GH secretion rate, and peak amplitude in healthy aged individuals (16,20), and that GH-releasing drugs can normalize sleep (21). Taken together, these data suggest that in addition to normal aging, sleep disturbances such as sleep apnea may substantially affect GH secretion and action, and thereby, have additional impact on the potential effects of CPAP treatment.…”

“…However, to date, no study has examined the effects of CPAP ventilation on lean body mass (LBM), despite potential beneficial effects of such changes on body function. During normal aging, mean GH secretion decreases mainly due to diminished amplitude of spontaneous GH peaks, whereas peak frequency usually remains unchanged (16). Aging is also associated with decreased serum IGF1 levels, which correlate well with GH secretory peaks in both women…”

Interindividual differences in circadian rhythmicity and sleep homeostasis in older people: effect of a PER3 polymorphism

“…However, changes in circadian parameters with aging are less consistent than age-related changes of sleep parameters, and SWS in particular. Thus, some (Czeisler et al, 1992;Münch et al, 2005;Van Coevorden et al, 1991;Weitzman et al, 1982), but not all, studies report a decline in the amplitude of CBT, melatonin, and cortisol (Monk, 2005;Niggemyer et al, 2004;Zeitzer et al, 1999). The disparity of these findings points to rather large interindividual differences in sleep and circadian rhythmicity with age and leaves the question open as to what is driving these individual differences (Van Cauter et al, 2000).…”