A single dose of modafinil usually lasts 10–12 hours. Most individuals report that it begins to work within 30 to 60 minutes and that its effects peak two to four hours after taking it. Instead of abruptly ceasing, the feeling of attentiveness and concentration gradually wanes. Modafinil has a half-life of around 12 to 15 hours, so even after the obvious effects wear off, it can still interfere with sleep if taken late. It is often taken early in the morning to coincide with your natural daily schedule for optimal effects.
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