A 150mg dosage of armodafinil usually lasts 10 to 14 hours, depending on metabolism, age, and tolerance. It is intended to increase alertness and is widely used to treat narcolepsy, shift work sleep disorder, and obstructive sleep apnea. Most people notice the benefits within 1 to 2 hours of consumption. While it gives long-lasting alertness, avoid taking it late in the day to avoid sleep disruption. Always take your doctor's dosage recommendations seriously.