Modafinil is a pill that is mostly used to treat sleep problems like narcolepsy, obstructive sleep apnea, and shift work sleep disorder. It is a drug that helps you stay awake and stops you from sleeping too much during the day. The way modafinil works is thought to involve chemicals in the brain, but no one really knows how it works. It is known to raise amounts of chemicals that make you awake and aware, such as dopamine and adrenaline. Modafinil is usually taken by mouth and comes in a number of different brands, such as Provigil. It should only be taken as your doctor tells you to because it can have side effects and might not work well with other medicines.