Rutgers researchers say some patients quit newer insomnia drug after unsettling side effects

NEW JERSEY — A Rutgers-linked study found that roughly one in four people who posted online reviews of a newer prescription insomnia drug said they had stopped taking it or intended to stop, often because of disturbing sleep experiences and feeling groggy the next day.

The research focused on lemborexant, marketed as Dayvigo, which was approved in the United States in 2019 for the treatment of insomnia. Some users said the medication greatly improved their sleep, while others reported concerning effects such as sleep paralysis, vivid nightmares and lingering drowsiness.

Scientists from the Rutgers Brain Health Institute, Virginia Commonwealth University and the University of Sydney reviewed 260 online comments about lemborexant posted from 2020 through 2023. Their analysis appeared in the journal Sleep Medicine.

Insomnia, marked by difficulty falling asleep or staying asleep, affects about 30% of adults, according to prior sleep research. Lemborexant is part of a newer group of insomnia drugs that target orexin, a chemical messenger that helps keep people awake, rather than broadly sedating the brain the way many older sleep aids do.

Clinical trials have shown that lemborexant can help people fall asleep more quickly and stay asleep longer than a placebo. But the Rutgers-led study aimed to learn how patients describe the drug in everyday use, especially the side effects that may shape whether they continue treatment.

Among the 260 reviewers, 70 said they had stopped taking the medication or planned to do so. Those users were less likely to say their sleep improved, though complaints about poor or interrupted sleep were still common among people who kept taking the drug.

The biggest differences between the two groups involved side effects. Sleep paralysis — a brief state in which a person is awake but cannot move or speak — appeared in 40% of reviews from people who stopped or planned to stop, compared with 15% of reviews from others. Vivid dreams, nightmares and next-day grogginess were also reported more often by those considering discontinuation.

“What surprised us most was how unsettling some patients found certain side effects,” said Abanoub J. Armanious, a pharmacoepidemiologist and neuropsychiatry researcher at the Rutgers Brain Health Institute and lead author of the study. “For these individuals, stopping the medication was not simply about it failing to improve sleep.”

Patient responses varied widely, with the most common rating being 1 out of 10, followed by 10 out of 10. About one-third of reviewers said the medication meaningfully improved their sleep, while half said it provided little or no benefit. Roughly two-thirds mentioned at least one side effect.

“It feels like I am sleeping naturally like I did once upon a time,” one online reviewer wrote, giving lemborexant a 10 out of 10.

Another reviewer described a frightening episode of sleep paralysis and rated the drug a 1.

“Felt paralyzed to move. Wanted to scream and could not make a sound,” the reviewer wrote. “Was able to touch my husband’s arm and waken him. He said he never saw such terror in my eyes.”

Other users described unusually intense dreams and nightmares that helped drive their decision to stop treatment.

“The dreams [nightmares] are VERY vivid and that’s the reason I can no longer take this medication,” one reviewer wrote.

Researchers said one possible explanation for the nightmares and sleep paralysis involves rapid eye movement sleep, the stage tied to dreaming. During this stage, the brain typically keeps most muscles from moving. Because blocking orexin can increase dream sleep, the team suggested that vivid dreams and temporary muscle paralysis may sometimes spill over into moments of wakefulness.

Not every patient viewed the unusual dreams negatively. One reviewer who gave the medication a 9 out of 10 said they looked forward to the “wild crazy dreams.”

“One of the important messages from our study is that lemborexant was reported to work very well for some people,” said Morgan James, senior author of the study, adjunct assistant professor at the Rutgers Brain Health Institute and Horizon Fellow and senior lecturer at the University of Sydney’s Brain and Mind Centre and School of Psychology.

The researchers cautioned that online reviews cannot show how often side effects occur among all people taking lemborexant. Those with especially positive or negative experiences may be more likely to write reviews, which means the comments may not reflect the broader patient population.

In the drug’s two main clinical trials, which followed all enrolled participants, fewer than 2% of those taking lemborexant experienced sleep paralysis, while about 1% to 3% reported nightmares or abnormal dreams. By contrast, about one in five online reviewers mentioned sleep paralysis, and nearly one-third described vivid dreams or nightmares.

“A clinical trial can tell you how often side effects occur,” Armanious said. “It is less equipped to tell you how much that side effect matters to the person living it. A side effect can be rare and still be the reason someone discontinues treatment.”

Most reviewers had taken the medication for less than a month, especially those who stopped or planned to stop. People who reported longer-term use generally gave the drug higher ratings, though the researchers said the study could not explain why those differences existed.

The findings underscore the need to discuss possible side effects and individual treatment needs with health care providers. Researchers said patients should be informed about potential reactions without being unnecessarily alarmed and should speak with a clinician before stopping or changing any prescribed sleep medication.

“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.

The research received partial support from the National Institute on Drug Abuse, part of the National Institutes of Health, through grants DA045765 and DA063103, along with a Horizon Fellowship from the University of Sydney. The researchers said the findings do not necessarily reflect the official views of the National Institutes of Health.

The Rutgers Brain Health Institute is also studying whether orexin-based sleep medications could one day be used to treat sleep problems linked to psychiatric conditions, including addiction.