Most Modafinil effects peak 2–4 hours after consumption. This time has the largest impact on alertness, attention, and weariness. Brain neurotransmitters like dopamine are stimulated by modafinil, improving cognitive function and alertness. Suitable for narcolepsy, sleep apnea, and shift work sleep disorder, Modalert 200 lasts 10–12 hours. For best results, use Modafinil in the morning or before work to prevent interrupting nocturnal sleep. Following your doctor's instructions and monitoring your body's reaction to the medicine is important since response timeframes vary.