HIGHER PLASMA IGF-1 LEVELS ARE ASSOCIATED WITH INCREASED DELTA-SLEEP IN HEALTHY OLDER MEN

Background. Sleep quality declines with age, with less time in deep or slow wave sleep (SWS) and reduced amplitude of the delta waves that c haracterize it. Age-related declines also occur in lean body mass, gro wth hormone (GH), and insulin-like growth factor 1 (IGF-I). These chan ges in sleep quality and anabolic status may be related, as administra tion of GH or growth hormone releasing hormone (GHRH) can enhance SWS and decrease awakenings in young men. Here we examine the relationship between plasma IGF levels and delta sleep quality in older men. Metho ds. The sleep EEG of 30 healthy elderly men (64 +/- 6 yrs; range 50-75 ) was recorded on the second of 2 consecutive nights. Plasma samples w ere drawn within 3 weeks of EEG recording, and IGF levels were assayed by RIA after acid extraction. Results. IGF explained 28% (semi-partia l correlation coefficient r = .53; p = .003) of the variance in averag e delta energy per epoch of SWS, after age-related variance was remove d. Higher IGF was associated with higher average delta energy. Similar results were obtained for total delta energy during SWS (r = .37, p = .04) 4nd time spent in SWS (r = .42, p = .02). Other measures of slee p quality (e.g., wakefulness, REM sleep) were not correlated with IGF. The IGF delta relationship was minimally influenced by moderator vari ables such as thyroxine (T3, T4), and/or body mass index (BMI). Conclu sion. We conclude that age-adjusted IGF levels in healthy senior men c o-vary significantly with SWS and the delta energy that characterizes it.