Insomnia is a sleep disorder characterized by difficulty falling asleep, difficulty staying asleep during the night or early awakening. Sleep is thus insufficient and non-restorative, compromising normal daytime activity and reducing the quality of life of who suffers from it. Insomnia is a complex, transient or chronic disorder that presents a variety of symptoms: drowsiness, headache, fatigue, malaise, irritability, difficulty in attention and concentration, memory deficit. It is generally associated with psychological disorders, such as depression and anxiety, or physical disorders, such as respiratory disorders and chronic pain syndromes, or with the use of drugs or, again, with excessive consumption of foods containing caffeine and alcohol abuse.