Sleep disorders are problems with sleeping. These include trouble falling or staying asleep, falling asleep at the wrong times, too much sleep, and abnormal behaviors during sleep.
There are more than 100 different sleeping and waking disorders. They can be grouped into 4 main categories:
Insomnia includes trouble falling asleep or staying asleep. Episodes may come and go, last up to 3 weeks (be short-term), or be long-lasting (chronic).
Hypersomnia is a condition in which people have excessive daytime sleepiness, meaning that they feel tired during the day. Hypersomnia can also include situations in which a person needs to sleep a lot. This may be due to other medical conditions, but can also be due to a problem in the brain. Causes of this problem include:
When no cause for the sleepiness can be found, it is called idiopathic hypersomnia.
Problems may also occur when you do not stick to a regular sleep and wake schedule. This occurs when people travel between time zones and with shift workers who are on changing schedules, especially nighttime workers.
Disorders that involve a disrupted sleep schedule include:
Abnormal behaviors during sleep are called parasomnias. They are fairly common in children and include: