Most of us go through our daily lives within one of two states of consciousness: sleep and wakefulness, with little overlap between the two. We may periodically become tired or rundown during the day, and need a little nap to refresh us. We may even doze off occasionally during a boring lecture or a dull movie. But for the most part, when we're awake, we're awake, and when we're asleep, we're asleep.
Now try to imagine what it would be like to live with a condition in which you rarely ever felt fully awake and hardly ever felt fully asleep; existing in a perpetual state where your life always feels caught in between the two, and without a moments notice may suddenly slip from one to the other. For sufferers of the sleep disorder narcolepsy, this is daily life.