Insomnia is too little or poor-quality sleep caused by one or more of the following:

• Trouble falling asleep
• Waking up a lot during the night with trouble returning to sleep
• Waking up too early in the morning
• Having un-refreshing sleep (not feeling well rested), even after sleeping 7 to 8 hours at night

Insomnia can cause problems during the day, such as excessive sleepiness, fatigue, trouble thinking clearly or staying focused, or feeling depressed or irritable. It is not defined by the number of hours you sleep every night. Although the amount of sleep a person needs varies, most people need between 7 and 8 hours of sleep a night.