The usual duration of modafinil-containing medication, Modalert 200, is 10 to 12 hours. People with sleep problems such as narcolepsy, sleep apnea, or shift work sleep disorder are intended to benefit from it by being more aware and awake. The drug typically takes effect one to two hours after use and offers decreased weariness, mental clarity, and prolonged attention throughout the day. But the precise amount of time can change based on a person's metabolism, age, and other medical conditions. Taking Modalert 200 early in the day is advised to prevent sleep disruptions. Observe your physician's instructions at all times to guarantee safe and efficient use.