When to Stop

• Sleep paralysis — ~1-2% trial incidence, more user-report prominence than daridorexant. Self-limited; can be terrifying first time. Watch period: any time on drug, clusters early.
• Hypnagogic / hypnopompic hallucinations — ~1-2% trial incidence. Vivid perceptions on falling asleep or waking. Generally benign, occasionally distressing.
• Cataplexy-like leg weakness — rare, transient. Class effect of OX2 blockade; suvorexant shows it at slightly higher rates than daridorexant per FDA labels.
• Complex sleep behaviors (sleepwalking, sleep-driving, sleep-eating with no recall) — suvorexant carries an FDA black-box warning for complex sleep behaviors as part of the broader hypnotic-class warning, though incidence in trials was low. This is a meaningful safety distinction from daridorexant (which does not carry this warning post-2019 hypnotic-class update).
• Suicidal ideation — class warning across CNS depressants in US labeling. Suvorexant clinical trials showed a numerical excess of suicidal ideation events on drug vs placebo (small numbers, not formally significant, but enough to keep the class warning in the label and enough that prescribers should screen for suicidality before initiation). This is a real signal in the FDA medical review document and is more pronounced than for daridorexant.
• Driving impairment next-day — Vermeeren 2015 RCT showed measurable impairment at 9 hours post-dose at 20 mg. Label carries explicit warning. Don't drive in the morning if you took suvorexant the night before, especially the first week.
• Compromised respiratory function in severe OSA — labeling caution. Mild-moderate OSA was studied; severe still flagged.
• First 2 weeks: parasomnia/sleep paralysis/hallucination watch. Most reports cluster early.
• First month at 15-20 mg: next-day function watch. If grogginess persists past 2 weeks, drop to 10 mg or switch class.
• Suicidal ideation screening: prescribers should ask before initiation, especially in patients with prior history.