The short answer
We do not know yet if retatrutide causes insomnia. The trial results released so far list stomach side effects, like nausea, diarrhea, constipation, and vomiting, as the most common ones. Trouble sleeping is not on that list.3,4
Retatrutide is not approved by the FDA or any other regulator. It is only legal to take inside a clinical trial.1 Products sold online as "reta" are not the same thing, and no one knows what is really in them.
"Is it the shot, or is it me?"
Many of my friends have tried the newer weight loss medicines, like Ozempic, Mounjaro, and lately Zepbound. Most have done really well. They lost weight and feel great.
But a few came to me with the same question. They felt tired all the time, yet could not sleep at night. They had trouble falling asleep, woke up during the night, and felt wired at bedtime and wiped out in the morning. They wanted to know: was it the medicine, or had their routine changed?
Now I hear more and more people talking about the next one, retatrutide, or "reta." So here is what we actually know about it and sleep, and what we do not.
What retatrutide is
Retatrutide is an experimental weight loss medicine made by a large drug company. It is a weekly shot. Ozempic works on one gut hormone (GLP-1), and Zepbound works on two. Retatrutide works on three: GLP-1, GIP, and glucagon.3 That is why people call it a "triple agonist."
It does not have a brand name yet. A drug usually gets one around the time it is approved.
Where retatrutide stands today
Retatrutide and sleep: what we know, and what we do not
What we know
- Sleep apnea improved. In TRIUMPH 1, people with moderate to severe sleep apnea started at about 59 breathing pauses per hour. That number dropped by up to 36 per hour, or about 61%.5
- Insomnia is not a top side effect so far. The most common side effects reported were nausea, diarrhea, constipation, and vomiting.4,5
- Heart rate went up. In the phase 2 trial, heart rate rose with higher doses, peaked at 24 weeks, then came back down.3,6
What we do not know yet
- How often people in the big trials had trouble sleeping. Full data has not been published.
- How it affects sleep in women in perimenopause or menopause.
- What happens to sleep over many years of use.
- What is really inside products sold online as reta.
Why does heart rate matter for sleep? A faster heartbeat at night can make it harder to settle down. Researchers said the heart rate change needs more study.6 If you ever notice your heart racing at night on any medicine, tell your doctor.
Why black market reta is a real risk
I always tell people to be careful with anything that is not approved. You hear people online saying they get great results with reta. But the manufacturer has not had it approved for sale anywhere in the world. Products made and sold outside of the trials are not regulated, and that could mean side effects nobody expects. There may be sleep side effects too, but we cannot know, because we do not know what people are really taking.
The manufacturer warns that products sold as retatrutide "may contain unknown ingredients, harmful contaminants and impurities," and can have too much or too little of the drug.1
A 2026 study looked at 378 people who took retatrutide outside of trials. 57% got it from online or telehealth sellers, and 29% from compounding pharmacies. After one year, they lost about 7% of their weight, compared with about 16% in the trials. The study also linked unapproved use with more heart related symptoms. It is a preprint, which means it has not been peer reviewed yet.7
Watch for these red flags
- "For research use only" or "not for human use" on the label.
- Sold without a prescription, or shipped as a powder you mix yourself.
- Any claim that it is "the same as" the retatrutide used in trials.
Why waiting for approval matters
New drugs come with a lot of data before they are approved. That is the whole point of the approval process. A drug has to show it is safe and works in many trials, with thousands of people, over many years. Once a drug is approved, people can feel confident trying it, because it has met that bar.
The approval process also sets the dose, the warnings, and the side effects listed on the label. Large trials can find side effects that small groups miss. That is the information you need to decide if a sleep change is from the medicine.
If your sleep changes on any weight loss medicine
Whether you take Ozempic, Wegovy, Mounjaro, Zepbound, or another medicine, sleep changes can come from the drug or from new habits. Ask yourself:
- Did my meal times change? Am I eating less, or eating later?
- Do I feel hungry, sick to my stomach, or have heartburn at night?
- Did I start working out harder, or later in the day?
- Has my bedtime or wake time moved around?
- Do I feel my heart racing when I lie down?
I think a healthy routine matters most. Go to bed and wake up at the same times. Some people start a new medicine and push themselves too hard, and that can leave them more tired. Melatonin at the right dose can help signal your body that it is time for sleep, so you are not groggy in the morning.
Before you add melatonin or any supplement to a new medicine, check with your doctor or pharmacist. To learn more, read GLP-1s and sleep, how much melatonin should I take, tired but cannot sleep, and why you keep waking up at 3am.
Talk to your doctor if
- You cannot sleep for more than a few weeks after starting a new medicine.
- Your heart races, pounds, or skips at night.
- You snore loudly or stop breathing in your sleep.
- You feel low, anxious, or not yourself.
- You are thinking of buying a medicine online without a prescription.
Common questions about retatrutide and sleep
Does retatrutide cause insomnia?
We do not know yet. The trial results released so far list nausea, diarrhea, constipation, and vomiting as the most common side effects. Insomnia is not among them, but full data has not been published.4,5
Can retatrutide help sleep apnea?
In a large trial, retatrutide lowered breathing pauses in people with moderate to severe sleep apnea by up to about 61%.5 It is not approved for sleep apnea or anything else yet.
Is retatrutide FDA approved?
No. As of September 2026, the manufacturer says it has not been approved by any regulatory agency. It is only legal to take inside a clinical trial.1
What is the brand name for retatrutide?
It does not have one yet. Its research code is LY3437943. A brand name usually comes around the time a drug is approved.
Can I take melatonin with retatrutide?
Retatrutide is only legally available in clinical trials. If you are in a trial, ask your study team before adding any supplement, including melatonin.
Is compounded or "research" retatrutide safe?
No one can say, because these products are not regulated. The manufacturer warns they may contain unknown ingredients or the wrong amount of the drug.1
Sources
- Eli Lilly and Company. What to know about retatrutide. Updated September 2026.
- Drugs.com. Retatrutide FDA approval status and development timeline. 2026.
- Jastreboff AM, Kaplan LM, Frías JP, et al. Triple-hormone-receptor agonist retatrutide for obesity: a phase 2 trial. New England Journal of Medicine. 2023;389(6):514-526.
- American Diabetes Association. Retatrutide results from TRIUMPH-1 and TRANSCEND-T2D-1, press release, 86th Scientific Sessions. June 2026.
- Sleep Review. Lilly's investigational triple agonist retatrutide reduces OSA severity in phase 3 trial. June 23, 2026.
- TCTMD. Dramatic weight loss, cardiometabolic improvement with retatrutide. 2023.
- Accelerating use of unapproved retatrutide is associated with weaker weight loss and increased cardiovascular symptoms. Preprints.org, 2026 (not yet peer reviewed). Reported by the Partnership for Safe Medicines, August 2026.
Tyler Smith, RN, BSN, BA is a registered nurse and the founder of Driffly. He writes and reviews the articles in the sleep education hub. About Tyler
The author is the founder of Driffly, a sleep supplement brand. Driffly does not sell retatrutide or any prescription medicine. This article is for education and is not medical advice. Talk to your doctor before starting, stopping, or changing any medicine.