Sleep-wake disorders can disrupt a person's ability to remain alert during the day or at work. Modafinil is used in adults with excessive sleepiness associated with narcolepsy, OSA, and shift work disorder. Its primary purpose is to promote wakefulness rather than directly correct every underlying sleep problem. For OSA, treatment of the airway obstruction remains an important part of medical care. Discussing persistent tiredness with a healthcare professional can help identify appropriate treatment.