[4] The difference is that after a sleep terror episode, the patient wakes up with more dramatic symptoms than with a nightmare disorder, such as screaming and crying.
Upon awakening, the sleeper is usually alert and oriented within their surroundings, but may have an increased heart rate and symptoms of anxiety, like sweating.
The sleeper may have recurring episodes of awakening while recalling the intensely disturbing dream manifestations which usually result from fear or anxiety, but can also be triggered by anger, sadness, disgust, and other dysphoric emotions.
[9] Nightmare disorders have negative consequences on several aspects of the patient's life, such as sleep, cognitive and emotional functioning and well-being.
[7] Other fields, such as interpersonal conflict, failure, helplessness, apprehension, being chased, accidents, evil forces, disasters, insects and environmental abnormalities may also feature in nightmares.
[13] First, the presence of frequent nightmares that imply danger for the person and impact mood in a negative way is needed.
[13] Finally, the disorder has to have a significant impact on the patient's personal, social or professional functioning, in areas like mood, sleep, cognition, behaviour, fatigue, family and occupation.
Nightmares can also be triggered by stress and anxiety and substance abuse, such as drugs that affect the neurotransmitters norepinephrine and dopamine and serotonin.
[5] Polysomnography records physiological parameters, such as electroencephalography (EEG), electromyography (EMG) and electrooculography (EOG) in a sleep laboratory.
[5] Consequently, assessment of nightmare disorders using polysomnography has to last for a longer period, in order to let the patient get used to the artificial environment.
[5] Indeed, when filling out questionnaires with questions about a long period, people often tend to underestimate the frequency of their nightmares because of forgetting.
[5] On the contrary, filling out a diary every day may lead to an overestimation of the numbers of nightmares, because of the focusing on this phenomenon.
[20][21][22] Therapy usually helps to deal with the frightening themes of the nightmares and alleviate the recurrence of the dreams.
[22] Eye Movement Desensitization and Reprocessing (EMDR) is a specialized intervention in which the focus is to stimulate neural mechanisms to induce disturbing memories and experiences.
[24] Silver, Brooks and Obenchain have found a decrease of the nightmares with Vietnam War veterans after 90 days of EMDR.
[22] Cognitive behavioral therapy for insomnia (CBT-I) is also efficient to treat nightmares in the PTSD population.
[12] The main objective is to work on changing maladjusted sleep habits and the trauma-related themes of nightmares.
Consequently, anxiety decreases, controllability increases, expectations change, which will impact the frequency of nightmares.
[24] Although these studies showed the efficacy of this therapy in the reduction of nightmare frequency on patients from the general population,[33] so far evidence for this treatment is still weak.
[34] Systematic Desensitization, using graduated exposure, has been shown to be efficient to treat chronic nightmares.
[12] Prazosin would significantly decrease the number of PTSD related nightmares and would therefore improve sleep quality.
[12] Benzodiazepines are also often used to treat nightmare disorder, despite the lack of efficacy demonstrated in empirical studies.
[24] Some other drugs as clonidine, cyproheptadine, fluvoxamine, gabapentin, nabilone, phenelzine, topiramate or trazodone have presented an amelioration of the nightmares.
[22] Furthermore, patients usually take more than one medication at a time, whatever the cause related to nightmares, leading to possible interactive effects.