Age-Related Changes in Slow Wave Sleep and REM Sleep and Relationship With Growth Hormone and Cortisol Levels in Healthy Men

DECREASED SUBJECTIVE SLEEP quality is one of the most common health complaints of older adults. The most consistent alterations associated with normal aging include increased number and duration of awakenings and decreased amounts of deep slow wave (SW) sleep (ie, stages 3 and 4 of non– rapid eye movement (non-REM) sleep). REM sleep appears to be relatively better preserved during aging. The age at which changes in amount and distribution of sleep stages appear is unclear because the majority of studies have been based on comparisons of young vs older adults. Several investigators have noticed that there are marked decreases in SW sleep in early adulthood in men but not in women. Sleep is a major modulator of endocrine function, particularly of pituitarydependent hormonal release. Growth hormone (GH) secretion is stimulated during sleep and, in men, 60% to 70% of daily GH secretion occurs during early sleep, in association with SW sleep. Whether decrements in SW sleep contribute to the well-known decrease in GH secretion in normal aging is not known. In contrast to the enhanced activity of the GH axis during sleep, the hypothalamic-pituitary-adrenal (HPA) axis is acutely inhibited during early SW Author Affiliations: Department of Medicine, University of Chicago, Chicago, Ill. Corresponding Author and Reprints: Eve Van Cauter, PhD, Department of Medicine, MC 1027, University of Chicago, 5841 S Maryland Ave, Chicago, IL 60637 (e-mail: [email protected]). Context In young adults, sleep affects the regulation of growth hormone (GH) and cortisol. The relationship between decreased sleep quality in older adults and agerelated changes in the regulation of GH and cortisol is unknown.