Belsomra (suvorexant) is a prescription medication for adults with insomnia, a condition characterized by trouble falling or staying asleep. It promotes sleep through a unique mechanism.
Understanding Sleep Regulation
The brain naturally regulates cycles of wakefulness and sleep through complex interactions of various neurotransmitters. A key system involved in maintaining wakefulness is the orexin, also known as hypocretin, system. Orexin neuropeptides, specifically orexin A and orexin B, are produced by specialized neurons located in the lateral hypothalamus of the brain.
These orexin neurons are highly active during periods of wakefulness, sending signals to other brain regions that promote arousal. They project widely to areas that stabilize the wake state and suppress sleep. The activity of these neurons decreases as an individual transitions into sleep, allowing the body to enter a restful state.
The balance between wake-promoting signals, like orexin, and sleep-promoting signals regulates the sleep-wake cycle. When the orexin system is overactive, it can lead to insomnia. Conversely, a deficiency in orexin can lead to conditions like narcolepsy, characterized by excessive daytime sleepiness.
How Belsomra Works
Belsomra operates by a targeted mechanism. It is categorized as a dual orexin receptor antagonist (DORA), meaning it specifically blocks orexin activity.
The medication works by reversibly binding to and inhibiting the two main orexin receptors, known as OX1R and OX2R. By occupying these receptors, Belsomra prevents the wake-promoting orexin neuropeptides (orexin A and orexin B) from attaching and signaling. This action effectively dampens the wakefulness drive.
Instead of directly inducing sedation, Belsomra “turns off” the signals that keep you awake, allowing natural sleep processes to occur. This suppression of wakefulness promotes the onset of sleep and helps maintain it throughout the night.
Distinguishing Belsomra from Other Sleep Medications
Belsomra’s mechanism of action sets it apart from other classes of sleep medications, such as benzodiazepines and Z-drugs like zolpidem. Benzodiazepines and Z-drugs primarily exert their effects by enhancing the activity of gamma-aminobutyric acid (GABA), the brain’s main inhibitory neurotransmitter.
These traditional medications work by increasing GABA’s calming effects, leading to sedation. In contrast, Belsomra does not interact with GABA receptors or other common neurotransmitter systems like serotonin, dopamine, or acetylcholine. Its unique approach lies in directly targeting the orexin system to reduce wakefulness, rather than broadly suppressing brain activity. This difference in mechanism represents a distinct strategy for treating insomnia.
Important Considerations for Use
Belsomra is approved for adults with insomnia. It is typically taken orally, usually within 30 minutes before going to bed, and only when at least seven hours of sleep are possible. Taking it with or right after a high-fat meal may delay its effects.
Common side effects include next-day drowsiness, headache, and dizziness. Patients should be aware of the potential for impaired alertness and driving the day after taking the medication. Less common, but more serious, side effects include temporary muscle weakness, sleep paralysis, and complex sleep behaviors like sleepwalking, where individuals may engage in activities without full awareness. Belsomra is contraindicated in individuals with narcolepsy, as it may worsen their symptoms.