A<unk>  is a dream which causes a strong unpleasant emotional response from the sleeper, typically fear or horror, or the sensations of pain, falling, drowning or death. Such dreams can be related to physical causes such as a high fever, or psychological ones such as psychological trauma or stress in the sleeper's life, or can have no apparent cause. If a person has experienced a psychologically traumatic situation in life—for example, a person who may have been captured and tortured—the experience may come back to haunt them in their<unk> s. Sleepers may waken in a state of distress and be unable to get back to sleep for some time.
Occasional<unk> s are commonplace, but recurrent<unk> s can interfere with sleep and may cause people to seek medical help. A recently proposed treatment consists of imagery rehearsal. This approach appears to reduce the effects of<unk> s and other symptoms in acute stress disorder and post-traumatic stress disorder.
Practitioners of lucid dreaming claim that it can help conquer<unk> s of this type, rather than of the traditional type (see below).
Nightmare
Postictal state
Moving pages
Face time
Watching pages
Golden hour 
Mean lifetime
Daytime wetting