There are many types of insomnia, including: 1. Primary insomnia: This is the most common type of insomnia, and it refers to difficulty falling asleep or staying asleep for more than a few hours at a time. 2. Secondary insomnia: This is when people have difficulty falling asleep or staying asleep because of a mental or physical health condition, such as anxiety or depression. 3. Insomnia due to a sleep disorder: This refers to a condition in which people have difficulty falling asleep or staying asleep because of a problem with their sleep habits, such as sleep apnea or restless leg syndrome. 4. Insomnia due to a medication: Some medications, such as antidepressants, can cause insomnia.