Narcolepsy is a serious type of sleep disorder that essentially involves drowsiness, daytime drowsiness, which is really profound for them and it gets to the point where they just have what are called sleep attacks and they will just fall asleep. The sleep attack can last for a period of 10 to 15 minutes and then they just wake up. When they wake up, they actually feel refreshed, but the periods can occur any time throughout the day. Now, that's what is different than sleep apnea, because in sleep apnea, when you have that, you wake and you don’t feel refreshed, but narcolepsy, they fall asleep and it's true sleep. I mean, they will actually wake up and feel refreshed, but they can't control it.