Researchers from Rutgers and other universities examined hundreds of online comments about lemborexant, a prescription sleep aid, and reported that roughly one in four reviewers indicated they had stopped or intended to stop using the medication because of unsettling side effects.
Insomnia, a disorder that disrupts the ability to fall asleep or stay asleep, affects approximately 30% of adults worldwide. The condition can lead to daytime fatigue, reduced concentration, and a decline in overall health. Lemborexant received U.S. approval in 2019 and represents a newer generation of sleep-inducing drugs that target the orexin system, a set of neurochemical pathways that promote wakefulness.
Lemborexant’s Mechanism of Action
In controlled trials, the drug, marketed under the name Dayvigo, shortened the time it took participants to drift off and extended the total duration of sleep compared with a placebo. By blocking orexin receptors, the medication reduces the brain’s alerting signals, which can also increase the proportion of REM sleep, sometimes producing vivid dreaming and a temporary reduction in muscle tone.
The research team, comprising scientists from the Rutgers Brain Health Institute, Virginia Commonwealth University, and the University of Sydney, collected 260 publicly posted reviews of the medication that were submitted between 2020 and 2023. These reviews were sourced from a variety of consumer-focused websites where patients share experiences with prescription drugs.
Side Effects and Discontinuation
The analysis, which appeared in the journal Sleep Medicine, revealed that 70 of the 260 reviewers either stopped or planned to stop taking the drug. Those individuals were less likely to claim the medication improved their sleep, yet they reported sleep quality complaints at a rate comparable to other commenters.
Adverse reactions such as sleep paralysis, vivid dreams, and next-day grogginess occurred more frequently among the group that discontinued use. Sleep paralysis—a brief episode in which a person is awake but unable to move or speak—was described by 40% of the discontinuers, while only 15% of the remaining participants mentioned this phenomenon.
One reviewer wrote, “It feels like I am sleeping naturally like I did once upon a time,” and gave the medication a perfect score of 10 out of 10. In stark contrast, another user assigned a rating of 1, describing episodes of sleep paralysis and intensely vivid dreams that disrupted nightly rest.
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Incidence of Dream-Related Effects and User Duration Insights
One reviewer gave the medication a 9 rating and said they anticipated “wild crazy dreams.” Researchers warned that posted comments may not reflect overall rates because extreme experiences are more likely to be shared. In the two key clinical trials, fewer than 2% of participants on lemborexant experienced sleep paralysis. About 1% to 3% reported nightmares or abnormal dreams during the study period.
“A clinical trial can tell you how often side effects occur,” Armanious said, noting that trials do not measure personal impact. He added that a rare side effect can still prompt discontinuation. Most reviewers, especially those who stopped or planned to stop, had used the drug for less than a month.
Variability in Patient Experiences
According to Abanoub J. Armanious, a pharmacoepidemiologist and neuropsychiatry researcher at the Rutgers Brain Health Institute, the most surprising finding was how disturbing certain side effects proved for some patients. He emphasized that the decision to stop the medication stemmed not only from a lack of sleep improvement but also from the intensity of the unwanted effects.
Morgan James, the senior author of the study, adjunct Assistant Professor at Rutgers Brain Health Institute and Horizon Fellow and senior lecturer at the Brain and Mind Centre and School of Psychology at the University of Sydney, noted that while many individuals reported strong benefits, roughly half of the reviewers described little or no improvement, and two-thirds mentioned experiencing at least one adverse reaction.
The researchers emphasized that the numbers can’t show how common any of these experiences are among all users, because people with the best or worst experiences are most likely to post. Anyone taking a prescribed sleep medication should talk with a clinician before stopping or changing it.
“What really stands out is how different people’s experiences with this medication can be, which highlights the importance of setting expectations and finding the right treatment for the individual,” James said.