David S Klein, MD
Insomnia is a sleep disorder that is characterized by difficulty falling and/or staying asleep. People with insomnia have one or more of the following symptoms:
Early Insomnia: Difficulty falling asleep
Mid-Insomnia: Waking up often during the night and having trouble going back to sleep
Late-Insomnia: Waking up too early in the morning
Functional Insomnia: Feeling tired upon waking
Primary insomnia is defined as sleep difficulty unrelated to a recognized health condition or problem.
Secondary insomnia is defined as sleep difficulty related or resulting from another medical condition or problem, such as asthma, pain, depression, arthritis, cancer, or heartburn. Medication side effects and certain foods/beverages can cause secondary insomnia.