Modafinil, also known as Provigil, is a prescription medication used to treat excessive daytime sleepiness due to narcolepsy, sleep apnea, and shift work disorder. It promotes wakefulness and alertness without addiction. The 200mg dosage, branded as Modvigil, can improve focus, concentration, and memory. Common side effects include headaches, nausea, anxiety, and insomnia. Modafinil is also used off-label to treat ADHD, depression, and chronic fatigue syndrome. However, using it without a prescription or for non-medical purposes is illegal and can have serious consequences. It is essential to consult with a healthcare provider to ensure safe use.