Insomnia, also known as sleeplessness, is a sleep disorder where people have trouble sleeping.  They may have difficulty falling asleep, or staying asleep as long as desired.  Insomnia is typically followed by daytime sleepiness, low energy, irritability, and a depressed mood.  It may result in an increased risk of motor vehicle collisions, as well as problems focusing and learning.  Insomnia can be short term, lasting for days or weeks, or long term, lasting more than a month.

Sleep apnea,  is a sleep disorder where a person has pauses in breathing or periods of shallow breathing during sleep.  Each pause can last for a few seconds to a few minutes and they happen many times a night.   In the most common form, this follows loud snoring.  There may be a choking or snorting sound as breathing resumes.  Because the disorder disrupts normal sleep, those affected may experience sleepiness or feel tired during the day.  In children it may cause hyperactivity or problems in school.