Physiology of growth hormone secretion during sleep.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing mechanistic human and animal physiological literature without systematic review methodology.
PubMed 8627466 · doi:10.1016/s0022-3476(96)70008-2
What was done
This narrative review summarizes findings from human and rodent studies on the temporal relationship between sleep architecture and growth hormone (GH) secretion, the mediating role of growth hormone-releasing hormone (GHRH), and age-related changes across the lifespan.
What was found
In adults, the primary pulse of GH secretion occurs shortly after sleep onset during the first phase of slow-wave sleep (SWS; stages III and IV). In men, approximately 70% of sleep GH pulses coincide with SWS, with secreted GH amounts correlating with concurrent SWS duration. GHRH administration decreases wakefulness and increases SWS in rodents and humans. Total 24-hour GH secretion decreases two- to threefold between ages 30 and 40 years, coinciding with a dramatic reduction in SWS.
Why it matters
It highlights that deep sleep architecture is closely tied to endocrine output and suggests that the age-related reduction in slow-wave sleep contributes significantly to the hyposomatotropism observed in aging.
Limits
The source is a narrative review without systematic search protocols, meta-analytic pooling, or formal risk-of-bias evaluation. Specific sample sizes and quantitative sex-stratified comparisons are not reported in the abstract.