Peptides for sleep are promoted to deepen sleep or reset the body clock, but none has been proven to treat insomnia. The three most discussed are epitalon, whose human studies measured melatonin rather than sleep; MK-677, which changed sleep stages in one small 1997 study; and Selank, a Russian anti-anxiety peptide with no sleep trials.[1][2][6] None is FDA-approved.[10]

What are peptides for sleep?

Sleep peptides are compounds sold online or through clinics on the idea that they work on the systems that set sleep timing and depth: melatonin from the pineal gland, growth hormone, whose release is tied to sleep, or the brain’s calming GABA system. They are not sleeping pills in the usual sense, and none has been studied the way approved insomnia drugs have.

The category is also loose. MK-677 is a small non-peptide molecule taken by mouth, designed by Merck to trigger growth hormone release through the ghrelin receptor.[20] It is sold alongside peptides because injected peptides such as ipamorelin act on the same receptor. For focus and anxiety uses of Selank, see nootropic peptides.

Browse all sleep peptides

How sleep peptides work

Each compound is linked to sleep through a different pathway:

  • Epitalon and melatonin: epitalon was designed from the amino-acid makeup of a cow pineal gland extract, epithalamin.[2] In older adults with low melatonin, epithalamin raised nighttime melatonin.[4] But in a study co-authored by Khavinson, epitalon applied to isolated rat pineal glands did not raise melatonin release.[5]
  • MK-677 and growth hormone: sleep and growth hormone release are closely linked.[1] MK-677 mimics ghrelin and, at 25 mg daily, nearly doubled 24-hour growth hormone in older adults.[17]
  • Selank and GABA: in rats, Selank changed the activity of genes involved in GABA signaling, the system that benzodiazepines and many sleeping pills act on.[18] A US pharmacology review grouped it with sedative-hypnotic agents but called it poorly studied.[19]

What sleep studies actually measured

Much of the online case for sleep peptides rests on studies that measured something other than sleep. Here is what each one tested.

Epitalon: a melatonin marker, not sleep

The best-described human studies of epitalon itself gave a sublingual spray to women working night shifts. In one, a melatonin marker rose about 1.7-fold from baseline in the 20 women given epitalon, while it did not change in the 20 given placebo, but the study did not measure how long or how well anyone slept.[2][3] FDA found no human study of epitalon that reported safety data.[2]

MK-677: sleep stages in 14 people

The 1997 Belgian study is the source of most MK-677 sleep claims.[1]

GroupDesignWhat changed
8 healthy young adults (18 to 30)Double-blind, placebo-controlled crossover; 7 days each of placebo, 5 mg and 25 mg at bedtimeAbout 50% more stage IV (deep) sleep and over 20% more REM sleep on 25 mg; fewer abnormal sleep patterns
6 healthy older adults (65 to 71)Two 14-day periods of 2 mg, then 25 mg; compared with baseline, no placeboNearly 50% more REM sleep and shorter time to REM sleep

These were healthy volunteers, not people with insomnia, and the study did not report daytime alertness. Later, longer trials of MK-677 focused on muscle and bone, not sleep.[8]

Selank: anxiety trials, not sleep trials

Selank’s Russian label lists stress-related sleep problems among its uses.[6] Its clinical studies measured anxiety, comparing it with benzodiazepines in small groups without placebo.[7] We found no trial that used sleep as its main outcome.

What a convincing sleep study would need

The AASM drug guideline graded insomnia medicines on randomized controlled trials in adults with chronic insomnia, looking at outcomes such as how long it takes to fall asleep, time awake during the night, total sleep time and sleep quality.[14] None of the sleep-peptide studies above meets that standard. The epitalon study measured a hormone marker in shift workers, the MK-677 study measured sleep stages in 14 healthy volunteers for one to two weeks, and the Selank studies measured anxiety.[1][2][7]

Short studies also miss the trade-offs. In the two-year MK-677 trial in older adults, two-thirds of people reported increased appetite and 44% had mild, short-lived swelling, compared with 36% and 27% on placebo.[8] A pill that deepens sleep stages but raises blood sugar is a different proposition from one that simply helps people sleep.

Peptides vs approved sleep treatments

Chronic insomnia has treatments backed by many randomized trials. The American Academy of Sleep Medicine (AASM) strongly recommends multicomponent cognitive behavioral therapy for insomnia (CBT-I) for adults.[15] Its separate drug guideline reviewed individual medicines, including several FDA-approved for insomnia, and graded each on the quality of the evidence.[14] That guideline also suggested that clinicians not use melatonin itself for chronic insomnia, which is worth keeping in mind when epitalon is marketed through its melatonin effects.[14]

Poor sleep can come from sleep apnea, depression, pain, medicines or other treatable causes. A doctor or sleep specialist can help identify the cause; this page is not treatment advice.

Safety, legality and sports rules

  • FDA approval: none of the three is FDA-approved for any use.[10]
  • Epitalon: removed from FDA’s safety-risk compounding category in April 2026 after its nomination was withdrawn. In July 2026, FDA advisers reportedly voted 7 to 5, with one abstention, to recommend compounding for insomnia, overriding FDA staff, who had recommended against it; FDA has not issued a final decision.[2][12] FDA also raised a theoretical cancer concern from telomerase activation.[2]
  • MK-677: FDA lists ibutamoren among compounding substances with significant safety risks, and its advisers voted 1 to 13 against it in 2024, citing fluid retention, heart failure and high blood sugar.[10][11] In a two-year trial, fasting blood sugar rose and insulin sensitivity fell,[8] and a hip fracture trial was stopped early over a heart failure signal.[9]
  • Selank: its US compounding nomination was withdrawn, and FDA says important human safety information is lacking.[10]
  • Unregulated products: in a JAMA analysis of 44 products sold online as “SARMs”, 39% contained other unapproved drugs, including ibutamoren.[16] “Research use only” vials are not checked for identity, purity or dose.
  • Sports: WADA names ibutamoren as a prohibited growth hormone secretagogue, banned at all times. Epitalon is not named, but in our reading, as an unapproved substance it falls under category S0.[13]

This is general information, not medical or legal advice.