About 10% of the population is believed to suffer from Primary Insomnia. It is also believed that people with chronic insomnia have a sleep system that is essentially out of alignment (we call this "homeostatic dysregulation"). We also know that a certain form of non-medication therapy called cognitive-behavioral therapy is a very effective treatment for insomnia. It is not known, however, whether cognitive-behavioral therapy actually works by bringing the brain's sleep system back into alignment ("sleep homeostasis"). One of the methods used to measure sleep homeostasis is to observe a person's brain waves during sleep and particularly during sleep that follows a period of sleep loss.