Approximately 15 million Americans work night or rotating shifts — and many suffer from Shift Work Sleep Disorder, a recognised circadian rhythm condition. Modafinil is one of only three medicines FDA-approved specifically for SWSD, with landmark clinical trial evidence showing significant shift-time alertness improvement. This complete guide covers how it works, the 200mg timing protocol, how long it lasts, and the non-pharmacological strategies that work best alongside it.