| What it is |
A prescription wake‑promoting agent (a “modulator of wakefulness”) approved in the U.S. for narcolepsy, obstructive sleep apnea, and shift‑work sleep disorder. |
| Mechanism of action |
Modafinil’s exact target is still being unraveled, but it is thought to inhibit the dopamine transporter (DAT) and influence several brain‑neurotransmitter systems (dopamine, norepinephrine, orexin/hypocretin, histamine, glutamate, GABA). The end result is increased cortical arousal without the “high” associated with stimulants. |
| Typical dosage |
• Narcolepsy: 200 mg once daily (usually at first awakening)
• Shift‑work: 200 mg 1–2 h before shift
• Sleep apnea: 200 mg 30–45 min before bedtime (usually once)
Do not exceed 400 mg/day. |
| Onset & duration |
Peak plasma ~2–3 h; total duration ~12–15 h. |
| Common side effects |
Headache, nausea, dizziness, insomnia (if taken late), dry mouth, anxiety or jitteriness. Serious but rare: rash, Stevens–Johnson syndrome, severe allergic reactions. |
| Contraindications |
Severe liver disease, heart failure, known hypersensitivity, concurrent use of strong CYP2C19 inhibitors (e.g., fluconazole). |
| Drug interactions |
• CYP2C19 inhibitors ↑ modafinil levels → ↑ side‑effects.
• CYP3A4 inducers (e.g., rifampin, carbamazepine) ↓ modafinil levels → reduced efficacy.
• Caffeine or other stimulants may compound CNS stimulation. |
| Legal status |
Prescription‑only in most countries. In the U.S. it is a Schedule IV controlled substance (less restrictive than stimulants but still regulated). |
| “Off‑label” use |
Commonly used as a cognitive enhancer by students, professionals, and people with ADHD, though evidence is mixed. Off‑label use carries the same risk profile and may be illegal in some jurisdictions. |
| Safety tips |
• Take it in the morning or at the start of your work shift to avoid insomnia.
• Do not exceed the prescribed dose.
• Avoid alcohol (may worsen dizziness).
• Discuss any heart condition or liver disease with your prescriber. |
| Monitoring |
Routine labs aren’t usually needed, but you should report any rash, mood changes, severe headaches, or breathing problems immediately. |
| Alternative wake‑promoters |
Caffeine (moderate), L‑citrulline, modafinil‑like agents (e.g., armodafinil, solriamfetol, pitolisant), non‑stimulant sleep hygiene. |