Provigil, the brand name for Modafinil, is widely prescribed to treat sleep disorders such as narcolepsy, shift work sleep disorder, and obstructive sleep apnea. Many people search for ways to buy Provigil online overnight due to convenience or urgency. However, Provigil is a prescription-only medication in the USA, and using it without proper guidance can lead to serious health risks. Understanding its medical purpose is the first step toward safe and responsible use.