Modvigil 200 mg tablets, typically last 10 to 15 hours, though this can vary depending on your metabolism, age, liver function, and level of sleep. The majority of people experience consistent wakefulness and enhanced focus after it starts to operate within one to two hours. Because of its lengthy half-life, if taken late, the effects may last into the evening and disrupt sleep. Tolerance, hydration, and other drugs all affect how each person reacts. Modafinil drugs should always be used under close medical supervision, particularly if the effects appear abnormally strong or mild.