Suvorexant and Daytime Fatigue: What Smartphone Ratings Found

“I slept better” and “I felt better the next day” deserve separate answers at an insomnia review. A morning note can also differ from an afternoon note.

What the phone prompts measured

The 2026 trial¹ included 40 adults aged 60–85, including 36 women. Participants received suvorexant or placebo for 16 nights, with phone symptom surveys four times daily. The active schedule began with two nights at 10 mg, then 14 at 20 mg. The manufacturer partly funded the study and supplied treatment.¹

The end-of-treatment fatigue questionnaire found no significant difference between groups. Repeated ratings detected an overall fatigue/sleepiness pattern across the day: estimates suggested worse mornings and better afternoons/evenings with suvorexant. However, every individual time-point confidence interval included no difference. The adjusted cognition analysis was not significant. These findings do not establish a dependable afternoon benefit.¹

Feeling less tired does not settle driving safety

The U.S. Belsomra label warns that impairment can occur without noticeable symptoms. It cautions people taking 20 mg against next-day driving and activities requiring complete alertness; lower doses can also impair driving. An afternoon rating is not a driving test.²

The label advises the lowest effective dose and at least seven hours before planned awakening. Other sedating medicines and alcohol can add to its effects. Those instructions need review against your actual prescription and morning responsibilities, rather than copying the trial’s dose increase.²

The suvorexant driving-safety guide covers that separate question. Report activities performed while not fully awake, such as sleepwalking or sleep-driving: the prescribing information instructs immediate discontinuation if a complex sleep behavior occurs.²

Make daytime effects part of the treatment review

Ask your clinician which observations would help between appointments and when to contact them about unwanted effects. If you make notes, distinguish drained energy from unintended dozing. Add the approximate time, when you took your medicine and what you were trying to do: read a page, prepare breakfast or finish an afternoon task.

A brief record might read, “8 a.m.: struggled to stay awake over breakfast; 3 p.m.: tired but could concentrate on a short letter.” Those are observations to discuss, not a score authorizing driving or a reason to adjust a dose yourself.

Medication review can also include other treatment options. NHLBI describes CBT-I as the usual first treatment for long-term insomnia, generally delivered over six to eight weeks, in person, by telephone or online.³

Did I Do That in My Sleep? distinguishes daytime sleepiness from feeling drained and asks readers to describe what changed after treatment. Use those questions to explain both the night and the following day.