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Online Reviews Describe Side Effects Insomnia Drug Trials Rarely Captured
In A Nutshell
- About one in five reviewers of the new insomnia drug Dayvigo described sleep paralysis, compared with roughly 1 percent or less in clinical trials.
- About a third reported more intense or disturbing dreams, and 68 percent described at least one unwanted effect.
- Reviewers who quit or planned to were more likely to mention sleep paralysis and disturbing dreams.
- Online reviews are self-selected, so the findings reflect patient experiences, not how often these effects occur in all users.
About one in five people who reviewed the sleep drug Dayvigo online described sleep paralysis, the terrifying feeling of being awake but unable to move or speak. That is far above what the clinical trials behind its approval reported. About a third of reviewers also described unusually vivid dreams or disturbing nightmares. Those figures come from a new analysis of 260 patient reviews posted on Drugs.com.
Dayvigo, the brand name for lemborexant, belongs to a newer class of insomnia drugs that block the signal of orexin, a brain chemical that promotes wakefulness. Approved in the United States in 2019, it was the second drug of its kind. Trials found it improved sleep, with mild next-day drowsiness the most common side effect and sleep paralysis rare.
Researchers from Rutgers University, Virginia Commonwealth University, and the University of Sydney wanted to know whether that picture holds up in everyday life. Their results, published in the journal Sleep Medicine, point to a bumpier experience for some patients.
Six Themes Emerged From 260 Dayvigo Reviews
Instead of a new trial, the team turned to Drugs.com, a US website where members of the public review medications and rate them from 1 (not effective) to 10 (most effective). They collected all 260 reviews from people prescribed lemborexant for insomnia, written between June 2020 and September 2023. More than half had previously tried other sleep drugs, such as Ambien.
Two researchers sorted comments into recurring topics, while a third checked that the sorting stayed consistent. Six broad categories covered everything from how fast the drug worked to its effects on mood. Drugs.com collects no demographic information, so reviewers’ ages, sexes, and health histories are unknown.
Dayvigo Side Effects Appeared Far More Often in Reviews Than in Trials
Sixty-eight percent of reviewers described at least one unwanted effect. Dream problems were among the most common: 32 percent reported more intense or disturbing dreams, and 21.5 percent described sleep paralysis. One reviewer wrote, “Felt paralyzed to move. Wanted to scream and could not make a sound.” Some also described hallucinations, such as hearing music that was not playing. A few reviewers said they looked forward to their vivid dreams.
In the approval trials, abnormal dreams and nightmares were reported by about 1 to 3 percent of participants, and sleep paralysis by no more than 1.1 percent. Safety tracking after the drug’s launch found similarly low rates. Online reviews are not directly comparable to trials, since people with strong experiences are more likely to post. Still, the researchers pointed to a separate analysis of reports sent to the US Food and Drug Administration, where sleep paralysis stood out as the strongest warning sign for Dayvigo compared with similar drugs.
One possible reason for the gap: trials usually screen out people with mental health conditions or a history of unusual sleep behavior, who may be more prone to disturbing dreams, and many reviewers reported mental health conditions. Orexin-blocking drugs also increase REM sleep, the stage of vivid dreams, and researchers have proposed that this may let the temporary muscle shutdown and imagery of dreaming spill into waking moments.
Next-day grogginess came up in about 18 percent of reviews, above the 4 to 13 percent seen in trials. Thirty percent of reviewers said their sleep meaningfully improved, one describing it as “sleeping naturally like I did once upon a time.” Half reported little or no perceived benefit from the drug.
Disturbing Dreams and Sleep Paralysis Were Linked to Quitting Dayvigo
About 27 percent of reviewers said they had quit or planned to. By comparison, the trials reported that 4 to 8 percent of participants stopped treatment because of side effects within six months, although the two figures are not directly comparable.
Quitters and would-be quitters were more likely to mention sleep paralysis (40 percent versus about 15 percent of the rest), disturbing dreams, and next-day sleepiness. Complaints about poor sleep quality, such as broken sleep, appeared at similar rates among quitters and those who stayed. One reviewer put the decision bluntly: “Paralysis and hallucinations are not acceptable to me.”
Ratings climbed with longer use, but 61 percent of reviewers had taken the drug for less than a month. That could mean the benefits take time to show, or that people with a rough start quit before giving it a fair try.
Most reviewers gave either a very low score or a very high one, with few in the middle. Reviews describing negative experiences tended to draw more likes from other readers, so the unhappiest voices may shape how others see the drug.
Researchers Suggest Early Warnings About Dayvigo Side Effects
Because reviews are self-selected, the authors treat their results as ideas to test, not firm advice. Even so, they suggest doctors tell patients up front about possible dream disturbances, sleep paralysis, and next-day sleepiness, especially early in treatment.
Anyone considering lemborexant should know that some people report disturbing dreams or sleep paralysis while taking it, and for some, those frightening nights are not worth the promise of better sleep.
Disclaimer: This article summarizes one published study and is for informational purposes only. It is not medical advice. Anyone with questions about a medication should talk with a doctor or pharmacist before starting, changing, or stopping it.
Paper Notes
Limitations
All reviews came from a single website, Drugs.com, which collects no demographic details, so the study cannot say anything about the age, sex, race, or health background of reviewers. Because people choose to post, the sample likely overrepresents especially strong positive or negative experiences, and reviewers knew they were taking an active drug, which may amplify both perceived benefits and blame for side effects. The data include no comparison with other sleep drugs, so the study cannot say how Dayvigo’s rates stack up against similar medications. Reviews are a snapshot in time rather than a record of how one person’s experience changed, though self-reported treatment duration offered a partial window. Two reviews were written by family members on behalf of patients, which could introduce differences in how experiences were described.
Funding and Disclosures
The study reports financial support from the National Institute on Drug Abuse for Morgan James and Caitlin Martin, and from National Health and Medical Research for Morgan James. Morgan James has a patent application pending. The authors state no other known competing financial interests. They also disclosed using ChatGPT for minor text editing during manuscript preparation and said they reviewed the output and take full responsibility for the content.
Publication Details
The study, titled “Perceived effectiveness, tolerability, and discontinuation of lemborexant in real-world use: Evidence from online patient reports,” was written by Abanoub J. Armanious, Alexandra R. Dunn, Caitlin E. Martin, and Morgan H. James, affiliated with Rutgers University, Virginia Commonwealth University, and the University of Sydney. It was published in Sleep Medicine, volume 149 (2027), article number 109264, and became available online on September 16, 2026. The article is open access under a CC BY license. DOI: https://doi.org/10.1016/j.sleep.2026.109264
