Clinical trial data show solriamfetol can modestly but reliably increase wakefulness in people with shift work disorder who start work very early in the morning; the main randomized study found a 9.4‑minute increase in objective sleep latency after four weeks versus placebo in 78 adults.
Trial signal and what it actually showed
The randomized study enrolled 78 adults with diagnosed shift work disorder (SWD) who began shifts between 3:00 and 7:00 a.m. After four weeks of treatment, solriamfetol increased objective wakefulness—measured as sleep latency—by an average of 9.4 minutes compared with placebo. That objective change was accompanied by lower Karolinska Sleepiness Scale (KSS) scores and better clinician and patient global impression ratings, indicating both measurable and felt improvements during typical eight‑hour shifts.
No serious adverse events were reported in the trial. Adverse events occurred in about half the treated participants, with headache and nausea the most common and generally mild. The result is a targeted signal: solriamfetol produces modest, sustained wakefulness gains over several hours for early‑morning SWD, not an immediate or universal cure for all shift‑related sleepiness.
Who matches the evidence and who should be cautious
The trial population—and the ongoing SUSTAIN study eligibility—helps define who the evidence applies to: adults aged 18–65 working regular early‑morning or night schedules (SUSTAIN specifies ≥5 night shifts per month with at least two consecutive shifts) and meeting diagnostic criteria for SWD. The primary randomized result came at four weeks; the larger SUSTAIN protocol uses a 12‑week treatment phase with frequent in‑person and remote visits to monitor effects and safety.
Workers without a confirmed SWD diagnosis, those who have other untreated sleep disorders, or people who cannot tolerate mild side effects should be cautious. The trial did not test every shift pattern (for example, rotating or very infrequent early starts), so clinicians should avoid extrapolating the 9.4‑minute average benefit to all shift workers.
Safety, monitoring and practical thresholds for continuing treatment
Because the benefit in the randomized study was measurable but modest, clinical decisions hinge on paired objective and subjective improvements and on tolerability. A practical starting approach is: confirm SWD, document baseline KSS and functional impairment, and recheck after 4 weeks for objective and patient‑reported gains. If a worker reports meaningful reduction in daytime impairment and the clinician notes improved global impressions without intolerable side effects, continuation is reasonable; otherwise pause and reassess for other causes.
Key stop signals include intolerable or worsening side effects (for example, persistent headache or nausea that interferes with work), new concerning symptoms, or lack of meaningful improvement in sleepiness or daytime functioning after a prespecified trial period (see table). The SUSTAIN protocol’s 12‑week treatment window is a practical checkpoint for longer‑term decisions, while the 4‑week result provides the earliest evidence of objective change.
Decision checkpoints and quick reference
| Decision point | What to measure | Threshold favoring continuation | When to stop or reassess |
|---|---|---|---|
| Eligibility | Confirmed SWD diagnosis; shift start 3–7 a.m.; 18–65 years; regular shift frequency | Meets SUSTAIN‑style criteria (≥5 shifts/month, ≥2 consecutive) | No formal SWD diagnosis or other untreated sleep disorder |
| Early signal (4 weeks) | Objective sleep latency; KSS; patient global impression | Objective gain (~9.4 min) plus meaningful KSS improvement or functional benefit | No subjective functional improvement despite objective tests, or intolerable side effects |
| Longer term (up to 12 weeks) | Sustained daytime functioning, ongoing side‑effect profile | Sustained symptomatic relief and tolerability | Persistent excessive sleepiness or new health concerns |
Common questions
Who should consider solriamfetol for SWD? Adults 18–65 with a confirmed SWD diagnosis who regularly start shifts between 3 and 7 a.m. and whose impairment is not controlled by behavioral measures.
How quickly should benefit appear and when to reassess? The randomized trial showed objective change at four weeks; reassess both objective tests and patient‑reported functioning at that point, with a fuller judgment by 12 weeks per SUSTAIN‑style monitoring.
What are clear reasons to stop? Intolerable side effects (headache or nausea interfering with work), new concerning symptoms, or no meaningful functional improvement after the prespecified trial period.