• Sleep Onset Insomnia (Delayed Sleep Phase Syndrome): A disorder in which the major sleep episode is delayed in relation to the desired clock time that results in symptoms of sleep onset insomnia or difficulty in awakening at the desired time. Idiopathic Insomnia: A lifelong inability to obtain adequate sleep that is presumably due to an abnormality of the neurological control of the sleep-wake system. The insomnia is long-standing, commonly beginning in early childhood, sometimes since birth.
• Psychophysiological Insomnia: A disorder of somatized tension (conversion of anxiety into physical symptoms) and learned sleep-preventing association that results in a complaint of insomnia and associated decreased functioning during wakefulness.
• Childhood Insomnia (Limit-Setting Sleep Disorder): Primarily childhood disorder that is characterized by the inadequate enforcement of bedtimes by a caretaker with resultant stalling or refusal to go to bed at the appropriate time.
• Other Childhood Insomnia: Another kind of insomnia that generally affects children is call Sleep-Onset Association Disorder. This disorder occurs when sleep onset is impaired by the absence of a certain object or set of circumstances, such as being held, rocked or nursed; television watching, radio listening, etc. (Could be true for the Parents cartoon character Linus and his blanket?)
• Food Allergy Insomnia: A disorder of initiating and maintaining sleep due to an allergic response to food allergens. It is typically associated with the introduction of a new for or drink.
• Environmental Insomnia (Environmental Sleep Disorder): A sleep disturbance due to a disturbing environmental factor that causes a complaint of either insomnia or excessive sleepiness. (How about the garbage man or the leaf blower early in the morning?)
• Transient Insomnia (Adjustment Sleep Disorder): Represents sleep disturbance temporally related to acute stress, conflict or environmental change causing emotional agitation.
• Periodic Insomnia (Non 24-Hour Sleep-Wake Syndrome): Consists of a chronic (lasting a long time) steady pattern consisting of 1-2 hour daily delays in sleep onset and wake times in an individual living society. Altitude Insomnia: An acute (short and sharp course, not chronic) insomnia usually accompanied by headaches, loss of appetite, and fatigue, that occurs following ascent to high altitudes. (Unless you are a mountain climber or a mountain goat, this kind of insomnia won't apply).
• Hypnotic-Dependency Insomnia (Hypnotic-Dependent Sleep Disorder): Characterized by insomnia or excessive sleepiness that is associated with tolerance to or withdrawal from hypnotic medications.
• Stimulant-Dependent Sleep Disorder: Characterized by a reduction of sleepiness or suppression of sleep by central stimulants, and resultant alterations in wakefulness following drug abstinence.
• Alcohol-Dependent Insomnia (Alcohol-Dependent Sleep Disorder): Characterized by the assisted initiation of sleep onset by the sustained ingestion of alcohol that is used for its hypnotic effect. Toxin-Induced Sleep Disorder: Characterized by either insomnia or excessive sleepiness produced by poisoning with heavy metals or organic toxins.
  

Although the presence of one or more of these characteristics may help in assessment of the patient, none is present in every Insomniac. Three main types of Insomnia are: Delayed Sleep Onset, Impaired Sleep Continuity, and Early Morning Awakening. Insomnia is more common among females, older people, thin people, and the anxious and depressed. Low social economic status, poor education, chronic medical illness, recent life stresses, and use of alcohol also attribute to the occurrence of Insomnia.