A parasomnia is disruptive, undesirable behavior that occurs either exclusively during sleep or is exaggerated by sleep. The victim of a parasomnia may or may not be aware of these experiences. Parasomnias are a group of sleep disorders that involve unwanted events or experiences that occur while you are falling asleep, sleeping or waking up. Parasomnias may include jerking body movements, change in behaviors, mood swings, perceptions or dreams. Although the behaviors may be complex and appear purposeful to others, you remain asleep during the event and often have no memory that it occurred. If you have a parasomnia, you may find it hard to sleep through the night.