A study showed GHRH, which promotes growth hormone (GH) release, and somatostatin (SST), which inhibits GH release, surge during REM sleep to boost GH. However, SST decreases, GHRH increases moderately during non-REM sleep. It stated little sleep reduces GH release, and too much GH causes wakefulness, suggesting sleep and GH form balanced system that aids metabolism and strengthens muscles, bones.