I. Insomnia
Insomnia is a disorder that causes difficulty falling asleep and/or staying asleep and that also affects daytime function. Adjustment insomnia, or acute insomnia, is associated with an identifiable life stress. Psychophysiological insomnia is characterized by anxiety about sleep. Idiopathic insomnia is not caused by any other illness and often begins in infancy or childhood. Inadequate sleep hygiene, such as excessive caffeine intake, also may cause insomnia. Insomnia may be associated with psychiatric disease, drug use, or other medical conditions.
Among the most common causes of insomnia, particularly in the elderly, is pain. Specifically, discomfort from arthritis, foot pain associated with diabetes, cluster headaches, angina, tumors, or ulcers may make sleep difficult.