This article is for research and educational purposes only and is not medical advice. It describes the body's own (endogenous) growth-hormone secretory physiology, not a property, benefit, or use-case of any compound.
Introduction
If you track your sleep, you have probably read that "growth hormone is released during deep sleep." That is one of the better-supported statements in sleep physiology, the body's largest growth hormone (GH) pulse is tightly coupled to slow-wave sleep. This article walks through what the research actually shows about the GH–sleep relationship, and keeps it strictly about endogenous physiology.
Quick answer: In healthy adults, the largest endogenous GH secretory pulse is associated with the onset of slow-wave (deep, non-REM) sleep, producing a nocturnal GH surge shortly after sleep onset. The amount of GH secreted is significantly associated with the amount of slow-wave sleep, and both slow-wave sleep and the nocturnal GH pulse decline with age. This is the body's own pulsatile hormone physiology.
GH Secretion and the Sleep Cycle
Endogenous GH is released from the anterior pituitary in discrete pulses rather than at a steady rate, so plasma GH rises and falls sharply around each secretory episode. Across the 24-hour cycle, the single most prominent of these episodes in healthy young adults occurs shortly after sleep onset, in association with the first period of slow-wave sleep.
The Sleep-Onset GH Pulse
That GH is secreted during sleep was first demonstrated in 1968 by Takahashi, Kipnis and Daughaday in the Journal of Clinical Investigation. Sampling plasma GH through the night in young adults, they reported that in 7 of 8 subjects a plasma GH peak lasting roughly 1.5–3.5 hours appeared with the onset of deep sleep. Two further observations tied the pulse to sleep itself rather than the clock: the GH peak was delayed when sleep onset was delayed, and a fresh peak appeared when subjects returned to sleep after a forced awakening. In men specifically, a substantial fraction of daily GH output, reported as approximately 70%, occurs during early sleep throughout adulthood.
Slow-Wave Sleep and GH Release
Beyond the timing of the first pulse, the physiology literature reports a quantitative coupling between the amount of slow-wave sleep (SWS) and the amount of GH secreted. In healthy men across the adult age range, GH secretion was significantly associated with slow-wave sleep (P<.001), independently of age, and awakenings were associated with decreased GH release. The direction has also been probed experimentally: pharmacologically increasing slow-wave sleep in young men produced a doubling of GH secretion, driven by a larger first GH pulse after sleep onset.
GHRH and the Reciprocal Relationship
The same hypothalamic neuropeptide that stimulates GH, Growth Hormone-Releasing Hormone (GHRH), also participates in sleep regulation. The sleep-onset GH pulse appears to be driven by a surge of GHRH during a period of relative somatostatin withdrawal. More broadly, in the neurochemical model of sleep, at least in males GHRH is described as a common stimulus of both non-REM sleep and GH secretion, a reciprocal interaction rather than a one-way link.
Sleep Loss and Ageing
Because the nocturnal GH pulse depends on slow-wave sleep continuity, fragmentation and sleep loss perturb the nocturnal somatotropic profile (awakenings accompany decreased GH release. Ageing illustrates the relationship over the lifespan: in healthy men, slow-wave sleep fell from about 18.9% of sleep in early adulthood (16–25 years) to 3.4% in midlife (36–50 years), paralleled by a major decline in GH secretion. This is descriptive physiology of how endogenous deep sleep and the endogenous nocturnal GH pulse decline together) not a suggestion of supplementation or restoration.
Frequently Asked Questions
When is growth hormone released during sleep? The largest endogenous GH pulse is associated with the onset of slow-wave (deep, non-REM) sleep, producing a surge shortly after sleep onset. This was first demonstrated in 1968, with a plasma GH peak lasting roughly 1.5–3.5 hours appearing with the onset of deep sleep.
Is the amount of GH related to how much deep sleep you get? Yes, in healthy men across the adult age range, GH secretion was significantly associated with the amount of slow-wave sleep, independently of age, and awakenings accompanied decreased GH release.
What role does GHRH play? The sleep-onset GH pulse appears driven by a GHRH surge during relative somatostatin withdrawal, and GHRH is also implicated in promoting non-REM sleep, pointing to a reciprocal GH-axis/sleep relationship, at least in males.
Does this mean a supplement or compound can boost "sleep GH"? No. This page describes endogenous GH secretory physiology, the body's own pulsatile hormone and its timing relative to deep sleep. It is not a property or use-case of any compound and makes no therapeutic or dosing claim.
References
- Takahashi Y, Kipnis DM, Daughaday WH. Growth hormone secretion during sleep. J Clin Invest. 1968;47(9):2079-2090. PMID 5675428
- Van Cauter E, Plat L, Copinschi G. Interrelations between sleep and the somatotropic axis. Sleep. 1998;21(6):553-566. PMID 9779515
- Van Cauter E, Leproult R, Plat L. Age-related changes in slow wave sleep and REM sleep and relationship with growth hormone and cortisol levels in healthy men. JAMA. 2000;284(7):861-868. PMID 10938176
- Steiger A. Neurochemical regulation of sleep. J Psychiatr Res. 2007;41(7):537-552. PMID 16777143