Does MK-677 improve deep sleep?

Yes. In the Copinschi 1997 study, high-dose MK-677 (25 mg) increased stage IV deep sleep duration by approximately 50% in young adults (ages 18-30) compared to placebo, measured by polysomnography. Deep sleep is the restorative phase associated with growth hormone release, tissue repair, and immune function.

How does MK-677 affect REM sleep?

MK-677 increased REM sleep by more than 20% in young adults and by nearly 50% in older adults (ages 65-71). It also decreased REM latency in older adults, meaning they entered REM sleep faster. REM sleep is associated with memory consolidation and emotional processing.

Should you take MK-677 before bed?

The clinical sleep study administered MK-677 at bedtime, which aligns with the natural GH pulse that occurs during early deep sleep. Bedtime dosing amplifies this natural rhythm. The most common reported side effect of bedtime dosing is increased morning appetite.

How long do MK-677 sleep benefits last?

The longest sleep-specific measurement was 14 days. Whether the sleep architecture improvements persist with chronic use is unknown. The 2-year Nass study confirmed sustained GH and IGF-1 elevation but did not measure sleep. Animal studies show desensitization of the GH response after 6 weeks, but whether this affects sleep-specific benefits through GH-independent pathways is unclear.

What are the side effects of MK-677 for sleep?

Common side effects include increased appetite (especially morning hunger), water retention, and mild edema. Metabolic concerns from longer use include increased fasting glucose (+0.3 mmol/L over 2 years), decreased insulin sensitivity, weight gain (+2.7 kg), and cortisol elevation (+47 nmol/L). A hip fracture trial in elderly patients was stopped early due to heart failure signals.

Is MK-677 better than melatonin for sleep?

MK-677 and melatonin work through completely different mechanisms. Melatonin regulates circadian timing and helps with sleep onset. MK-677 modifies sleep architecture by increasing deep sleep and REM sleep duration. No head-to-head trial has compared them. MK-677 carries metabolic side effects that melatonin does not.

MK-677 (Ibutamoren)

MK-677 and Sleep: Deep Sleep and REM Effects

13 min read|March 22, 2026

MK-677 (Ibutamoren)

50% more deep sleep

High-dose MK-677 increased stage IV (deep) sleep duration by approximately 50% in young adults compared to placebo, measured by polysomnography.

Copinschi et al., Neuroendocrinology, 1997

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MK-677 (ibutamoren) is an oral, non-peptide ghrelin receptor agonist that stimulates growth hormone secretion by mimicking the endogenous hormone ghrelin. Among its documented effects, the impact on sleep architecture stands out as one of the most consistent findings in the clinical literature. The pivotal 1997 study by Copinschi and colleagues demonstrated that bedtime administration of MK-677 increased stage IV (deep) sleep by approximately 50% and REM sleep by more than 20% in young adults, while older adults experienced a nearly 50% increase in REM sleep.^[1] These changes are not incidental side effects. Growth hormone and sleep are bidirectionally linked: the largest natural GH pulse occurs during stage IV sleep, and interventions that increase GH secretion tend to deepen sleep, while deeper sleep in turn promotes GH release.

Key Takeaways

In young adults (18-30 years), high-dose MK-677 increased stage IV deep sleep duration by approximately 50% and REM sleep by more than 20% versus placebo (Copinschi et al., Neuroendocrinology, 1997)
In older adults (65-71 years), MK-677 increased REM sleep by nearly 50% and decreased REM latency, with the frequency of sleep deviations dropping from baseline levels (Copinschi et al., 1997)
Sleep quality abnormalities decreased from 42% under placebo to 8% under high-dose MK-677 in young subjects (P < 0.03)
The 2-year Nass et al. RCT (65 healthy older adults) confirmed MK-677 was generally well tolerated but increased fasting glucose by 0.3 mmol/L, body weight by 2.7 kg, and cortisol by 47 nmol/L (Annals of Internal Medicine, 2008)
MK-677's sleep benefits are mediated through the ghrelin receptor (GHSR1a), which modulates sleep architecture through both growth hormone-dependent and independent pathways
Desensitization to GH-stimulatory effects occurs with prolonged use in animal models, but human sleep data beyond 14 days is limited

How Growth Hormone and Sleep Are Connected

Growth hormone secretion follows a circadian rhythm dominated by a large nocturnal pulse that coincides with the first episode of stage III/IV (slow-wave) sleep. This relationship is not coincidental. Hypothalamic GHRH (growth hormone-releasing hormone) neurons are active during slow-wave sleep onset and drive both GH release from the pituitary and sleep-promoting signals to the ventrolateral preoptic area.^[2]

As people age, both slow-wave sleep and GH secretion decline in parallel. By age 60, slow-wave sleep duration has typically decreased by 75% compared to young adulthood, and GH secretion has fallen by a similar magnitude. Whether the sleep loss drives the GH decline, the GH decline drives the sleep loss, or both deteriorate together from a common cause remains debated. What is clear is that interventions targeting the GH axis can modify sleep architecture, and MK-677 is the most studied example.

The Copinschi 1997 Study: Primary Sleep Evidence

The foundational evidence for MK-677's sleep effects comes from a study published in Neuroendocrinology by Copinschi, Van Cauter, and colleagues.^[1]

Study Design

The study enrolled two cohorts:

Young cohort: 8 subjects (ages 18-30) in a double-blind, placebo-controlled, three-period crossover design. Each subject received 5 mg MK-677, 25 mg MK-677, and placebo for 7-day treatment periods at bedtime, in randomized order, separated by at least 14 days
Older cohort: 6 subjects (ages 65-71) in two 14-day treatment periods (2 mg, then 25 mg MK-677), with a 14-day washout between periods

Sleep was measured objectively by polysomnography, the gold standard for sleep architecture assessment.

Results in Young Adults

At the high dose (25 mg):

Stage IV (deep) sleep duration increased by approximately 50% compared to placebo
REM sleep increased by more than 20% compared to placebo (P < 0.05)
The frequency of deviations from normal sleep patterns decreased from 42% under placebo to 8% under high-dose MK-677 (P < 0.03)
The low dose (5 mg) produced intermediate effects

Results in Older Adults

At 25 mg:

REM sleep increased by nearly 50% (P < 0.05)
REM latency (the time from sleep onset to first REM period) decreased (P < 0.02)
The frequency of deviations from normal sleep patterns decreased (P < 0.02)

The authors concluded that MK-677 may "simultaneously improve sleep quality and correct the relative hyposomatotropism of senescence," positioning the drug as a dual-benefit intervention for age-related GH decline and sleep deterioration.

Limitations

The study was small (14 total subjects), treatment periods were short (7-14 days), and the older cohort did not use a placebo control. Whether the sleep improvements persist beyond the initial weeks of treatment is unknown. The 5 mg dose in young adults and the 2 mg dose in older adults serve as partial dose-response data, but the dose-response relationship for sleep effects has not been systematically characterized.

The Ghrelin-Sleep Pathway

MK-677's sleep effects operate through the ghrelin receptor (GHSR1a, also called the growth hormone secretagogue receptor). The ghrelin system modulates sleep through at least two mechanisms:

GH-dependent pathway. By stimulating GH release, MK-677 amplifies the nocturnal GH pulse that naturally occurs during slow-wave sleep. This may reinforce the GHRH-mediated sleep-promoting circuit, deepening and prolonging stage III/IV sleep.

GH-independent pathway. Ghrelin receptor signaling in the hypothalamus and brainstem influences sleep-wake regulation independently of GH secretion. Polishchuk and colleagues' 2025 review documented that ghrelin modulates neuroprotection, stress reactivity, and sleep architecture through GHSR1a-dependent pathways that do not require GH release.^[3] This may explain why MK-677 affects REM sleep (which is not GH-associated) in addition to slow-wave sleep.

The bedtime dosing protocol used in sleep studies leverages both pathways: the drug activates GHSR1a as the brain transitions into sleep, amplifying both the natural GH surge and the ghrelin-mediated sleep-promoting effects.

What the Longer-Term Studies Show

While the Copinschi study focused specifically on sleep, the longer-term MK-677 trials provide context for what happens with sustained use.

Nass et al., 2008: The 2-Year RCT

The most comprehensive long-term MK-677 study randomized 65 healthy older adults (ages 60-81) to 25 mg MK-677 or placebo daily for 2 years. This study measured body composition and metabolic outcomes rather than sleep specifically, but several findings are relevant:^[4]

GH and IGF-1 levels increased to those of healthy young adults and remained elevated over 2 years, suggesting sustained ghrelin receptor activation
Fat-free mass increased by 1.1 kg (versus -0.5 kg in the placebo group, P < 0.001)
Fasting blood glucose increased by 0.3 mmol/L (5 mg/dL) with decreased insulin sensitivity
Body weight increased by 2.7 kg (versus 0.8 kg with placebo)
Cortisol increased by 47 nmol/L
Appetite increase was the most frequent side effect but subsided after a few months

The sustained GH and IGF-1 elevation suggests that GHSR1a activation does not fully desensitize with chronic use in humans, though the degree of GH response may diminish over time.

Desensitization Concerns

Lee and colleagues demonstrated in rats that 6 weeks of MK-677 administration abolished the GH response. The mechanism was an increase in hypothalamic somatostatin expression, which acts as a brake on GH secretion.^[5] Whether this translates to humans and whether it affects the sleep-specific benefits (which may operate through GH-independent pathways) is unclear. The Nass 2-year study suggests that at least some GH elevation persists in humans, but the sleep architecture was not measured in that trial.

Safety Considerations Relevant to Sleep Users

Several MK-677 side effects are relevant for anyone considering the drug primarily for sleep improvement.

Insulin resistance. The Nass study documented increased fasting glucose and decreased insulin sensitivity over 2 years. The Adunsky hip fracture trial (123 elderly patients, 25 mg/day) was terminated early due to a safety signal of congestive heart failure, though the study population was elderly and medically fragile.^[6]

Appetite stimulation. MK-677 consistently increases appetite, particularly in the first weeks of use, through MC4R-independent ghrelin receptor activation. For users taking it at bedtime specifically for sleep, this may manifest as morning hunger.

Water retention. Peripheral edema was reported in the Nass study and is a common user-reported side effect. GH itself promotes sodium and water retention.

Cortisol elevation. The Nass study showed a 47 nmol/L increase in cortisol. Sustained cortisol elevation could theoretically counteract sleep benefits, though the clinical studies suggest sleep improvements dominate the cortisol effect at the doses tested.

IGF-1 elevation and long-term safety. Sustained IGF-1 elevation raises theoretical concerns about cancer risk. No long-term cancer outcome data from MK-677 studies exists.

A case report by Cardaci and colleagues documented a 25-year-old male who took MK-677 (15 mg) alongside LGD-4033 (a SARM) for 5 weeks. The combination increased body mass by 6% and total fat mass by 15.4% while decreasing testosterone by 62.3% and HDL cholesterol by 36.4%.^[7] This case illustrates the risks of combining MK-677 with other compounds, a common practice in recreational use that has no controlled safety data.

Sigalos and Pastuszak's 2018 review of growth hormone secretagogue safety concluded that GHSs including MK-677 are "well tolerated" in available studies, with the primary concern being blood glucose effects from decreased insulin sensitivity. The review noted that long-term cancer and mortality data are absent.^[2]

MK-677 vs. Other Sleep Interventions

MK-677 is not actually a peptide; it is a small molecule that mimics ghrelin's action at GHSR1a. This distinction matters pharmacologically: its oral bioavailability and long half-life make it more convenient than injectable GHRP-6 or GHRP-2, which also activate the ghrelin receptor but require subcutaneous injection and have shorter durations of action.

Compared to pharmaceutical sleep aids like benzodiazepines or Z-drugs (zolpidem, eszopiclone), MK-677's mechanism is fundamentally different. Benzodiazepines enhance GABA signaling and tend to increase total sleep time but suppress slow-wave and REM sleep, the opposite of MK-677's effect. MK-677 appears to increase the restorative phases of sleep rather than simply prolonging unconsciousness.

Compared to melatonin, which primarily regulates circadian timing and sleep onset latency, MK-677 modifies sleep architecture itself, increasing both deep sleep duration and REM proportion.

No head-to-head trials compare MK-677 against any established sleep medication.

The Copinschi study tested MK-677 in both young and older cohorts specifically because sleep deterioration tracks alongside GH decline during aging. By age 35, most adults have begun losing slow-wave sleep. By age 60, many spend less than 5% of total sleep time in stage IV, compared to 15-20% in young adulthood. This progressive loss correlates with declining GH secretion, reduced muscle recovery, impaired immune function, and cognitive changes.

MK-677's ability to increase both deep sleep and GH in older adults addresses this dual decline at its source. The MK-677 sarcopenia data in elderly populations suggests that improved sleep architecture may contribute to the lean mass preservation observed in longer studies, though this connection has not been directly tested. The 2-year Nass RCT showed that fat-free mass increased in MK-677-treated older adults while declining in the placebo group, and sleep-mediated GH release is a plausible contributor to this effect.^[4]

What the Data Cannot Tell Us

The sleep evidence for MK-677 rests on a single study of 14 subjects with treatment periods of 7-14 days. The finding is biologically plausible, consistent with what is known about the GH-sleep axis, and shows a dose-response pattern. But several questions remain unanswered:

Whether sleep benefits persist beyond 2 weeks of nightly dosing
Whether desensitization of the GH response (documented in rats) also blunts sleep effects
Whether the insulin resistance and cortisol elevation from chronic use ultimately degrade sleep quality at longer timepoints
Whether the sleep improvements translate to measurable next-day cognitive or physical recovery benefits
What the minimum effective dose for sleep benefits is (5 mg produced intermediate effects in young adults, but was not compared against 25 mg in older adults)

The Bottom Line

MK-677 produces measurable improvements in sleep architecture, increasing both stage IV deep sleep and REM sleep in young and older adults. The effect is mediated through ghrelin receptor activation and occurs through both GH-dependent and GH-independent pathways. The evidence base is small (one study, 14 subjects, 7-14 day treatment periods) but biologically consistent and objectively measured by polysomnography. Longer-term MK-677 studies confirm sustained GH elevation over 2 years but did not measure sleep. The metabolic trade-offs of chronic use (insulin resistance, weight gain, cortisol elevation) must be weighed against the sleep benefits, and no data exists beyond 14 days of sleep-specific measurement.