Taking Adderall overnight is generally not recommended due to its stimulant properties, which can interfere with sleep. Adderall, a combination of amphetamine and dextroamphetamine, is typically prescribed for daytime use to manage symptoms of attention deficit hyperactivity disorder (ADHD) and narcolepsy. Its effects can last for several hours, depending on the formulation (immediate-release or extended-release), and taking it late in the day or overnight can lead to insomnia and disrupted sleep patterns.