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Q: Is it okay to borrow a friend's prescription for modafinil to help me stay alert?

A: Modafinil is meant to treat severe sleepiness resulting from serious disorders like narcolepsy, and it can be habit-forming. If you're having trouble staying alert during the day, you're probably not getting enough sleep. Try starting a sleep journal: Before bed each night, note your evening activities—drinking a glass of wine, surfing the Web—and then the next morning log how long it took you to fall asleep. Soon you'll notice patterns of activities that are keeping you awake.

Ask Dr. Oz a question, plus our advice on how to get better sleep