Belsomra (suvorexant) is a prescription sleep medication used to treat insomnia in adults who have trouble falling asleep, staying asleep, or both. It was the first in a newer class of sleep drugs that work differently from older options like benzodiazepines or “Z-drugs,” targeting the brain’s wakefulness system rather than broadly sedating it.
How Belsomra Works
Your brain has a chemical signaling system built around molecules called orexins, which act as powerful promoters of wakefulness. Throughout the day, orexins bind to two types of receptors in the brain to keep you alert and aroused. Belsomra blocks both of these receptors, essentially turning down the volume on your brain’s “stay awake” signal so sleep can take over naturally.
This is a fundamentally different approach from most older sleep medications. Traditional options tend to amplify the brain’s sedation pathways, which can produce heavy, sometimes groggy sleep. Belsomra instead reduces the drive to stay awake, which in theory allows sleep to unfold more naturally. The orexin system also plays a role in reward and motivation circuits, which is part of why Belsomra carries a lower risk of dependence compared to some older sleep aids, though it is still classified as a Schedule IV controlled substance by the DEA.
What the Clinical Trials Show
Belsomra’s strongest evidence is for sleep maintenance, meaning it helps people who wake up during the night and struggle to get back to sleep. In a year-long study, patients taking Belsomra spent about 33.5 fewer minutes awake during the night compared to their baseline, while the placebo group improved by about 24 minutes. A separate four-week trial found a similar reduction of roughly 33 minutes in nighttime wakefulness versus placebo.
These improvements are real but modest. If you currently lie awake for 90 minutes in the middle of the night, Belsomra might bring that closer to an hour. It is not a knockout pill, and some people find the effect underwhelming. That said, even 20 to 30 minutes of additional sleep can meaningfully improve how you feel the next day.
Common Side Effects
The most frequently reported side effect is next-day drowsiness, which affected about 7% of patients taking Belsomra in clinical trials compared to 3% on placebo. That drowsiness becomes more pronounced at higher doses: only 2% of patients at the lowest dose reported it, but 12% did at higher experimental doses.
Other side effects that showed up more often than placebo include:
- Headache (7% vs. 6% placebo)
- Dizziness (3% vs. 2%)
- Abnormal dreams (2% vs. 1%)
- Dry mouth (2% vs. 1%)
- Diarrhea (2% vs. 1%)
Like all prescription sleep medications, Belsomra carries warnings about complex sleep behaviors, meaning activities like walking, eating, or even driving while not fully awake. These events are rare but serious. Alcohol and other sedating substances increase the risk.
Why It’s Not for Everyone
Belsomra is specifically contraindicated in people with narcolepsy, and the reason ties directly to how the drug works. Narcolepsy is caused by a loss of orexin-producing neurons in the brain. Blocking the already-depleted orexin system with Belsomra would worsen the excessive sleepiness and could trigger cataplexy, a sudden loss of muscle tone that is a hallmark of narcolepsy.
People taking medications that slow down the liver enzyme responsible for breaking down Belsomra (known as CYP3A4 inhibitors) may need a lower dose, since the drug stays in the system longer. Common examples include certain antifungal medications and some antibiotics. Grapefruit juice can have a similar effect.
Belsomra in Older Adults
Insomnia becomes more common with age, and older adults are often more sensitive to sleep medications. In clinical trials, elderly patients were given 15 mg rather than the 20 mg used in younger adults. Side effect rates at these adjusted doses were similar between the two age groups.
Belsomra has also been studied specifically in patients with mild to moderate Alzheimer’s disease, a population where insomnia is extremely common and many sleep medications carry serious risks of falls and confusion. In a four-week trial of 285 patients, falls occurred in 2% of the Belsomra group versus none on placebo, while drowsiness affected 4% compared to 1%. These numbers suggest the drug is tolerable in this group, though falls remain a concern worth weighing.
How Belsomra Compares to Other Sleep Medications
Belsomra sits in a distinct category. Older benzodiazepine-type sleep aids and Z-drugs work by boosting the brain’s main inhibitory signaling system, which produces broader sedation and carries a higher risk of dependence, rebound insomnia, and next-day impairment. Belsomra’s orexin-blocking approach tends to produce less of the “hangover” feeling, though next-day drowsiness is still its most common side effect.
Since Belsomra’s approval, other orexin-blocking sleep medications have come to market, making this a growing drug class. The choice between them typically comes down to how quickly they take effect, how long they last, and how an individual responds. Belsomra is taken once per night, at least seven hours before you need to be awake. Because it is a controlled substance, prescriptions may have limits on refills depending on your state.