Modvigil (Modafinil) is a eugeroic that promotes alertness by activating the peripheral sympathetic nervous system. It is used to regulate and suppress attention deficit hyperactivity disorder (ADHD), as well as narcolepsy and other sleep disorders such as obstructive sleep apnea and shift work difficulties. Modvigil may help you stay awake for up to 12 hours. Modvigil is a lifesaver for those who suffer from obstructive sleep apnea,hypopnea syndrome, narcolepsy, or whose circadian rhythm is disrupted owing to working night shifts. This is known as shift work sleep disorder.