Parasomnias are sleep disorders that involve undesirable events and experiences. They occur during sleep, as you fall asleep or as you wake up. Some of these disorders are similar to one another. They share some common features.

The following chart will help you distinguish four of the parasomnias from each other. Some parasomnias may cause severe distress. In rare cases a parasomnia may put you or someone else at risk of an injury. You should contact an accredited sleep disorders center if you need medical help.

.	Nightmare disorder	REM sleep behavior disorder	Sleep terrors	Confusional arousals
How many adults it affects	Nightmares are common, but only about 2% to 8% have nightmare disorder.	Less than one percent	About two percent	3% to 4% of adults over the age of 15
Adults it affects most	Those who live through a traumatic event	Men over the age of 50, people with narcolepsy or Parkinson disease	Men and women under the age of 65	Those under the age of 35
Time when it tends to occur	Last half of the night	Last half of the night	First half of the night	First half of the night
Primary symptoms	Having a disturbing dream that causes you to wake up with a feeling of panic, a racing heart and rapid breathing	Acting out action-filled dreams of being attacked or chased with punching, kicking and running	Sitting up in bed with an unresponsive look of intense fear, sometimes with aggressive behavior	“Sleep drunkenness,” mental confusion, disoriented or even aggressive behavior
Sounds	Varies	Talking, shouting, laughing, or swearing	Loud scream or cry, incoherent sounds	Slow and confused talking, shouting
Eyes	Closed	Closed	Open	Open
Response if others try to wake you	Awaken quickly, become rapidly alert; emotional – fear, anxiety, disgust, relief	Awaken quickly, become rapidly alert	Unresponsive, confused and disoriented	Resistant or aggressive
Memory of the event	Clear recall of a dream	Clear recall of a dream	Little or none	Little or none
Primary side effects	Fear and anxiety, sleep avoidance	Injury to yourself or your bed partner	Injury to yourself or your bed partner	Injury to yourself or your bed partner

More Information
Preventing Parasomnias

Comparing Child Parasomnias

Reviewed by Nilesh Davé, MD
Updated July 18, 2007