Classically, the sleep-onset insomnia patients were thought to be anxious, whereas the individuals who struggled to maintain their sleep or who awoke too early were thought to be depressed. Most sleep experts do not subscribe to this way of thinking anymore. In reality, a good way to think about this is as follows: Anyone whose sleep is inefficient— meaning the time he sleeps divided by the time he is in bed is a low number, say less than 75 or 80 percent—has insomnia.
