Nightmare disorder is a parasomnia. A parasomnia involves undesired events that come along with sleep. Nightmares are disturbing, visual dream sequences that occur in your mind and wake you up from your sleep.
Nightmare disorder develops when you have nightmares on a frequent basis. This can cause someone to fear going to sleep. You may worry each night that you will have another nightmare. The nightmares also keep you from sleeping well. They cause you to feel anxious and scared when you wake up. This makes it hard for you to relax and go back to sleep again. This loss of sleep can cause you to have even more intense nightmares. These sleep problems can make you very sleepy during the day.
Nightmares seem very real. They become more disturbing as they unfold. They tend to involve the emotions of anxiety, fear, or terror. Other emotions that nightmares provoke include the following:
- Anger
- Rage
- Embarrassment
- Disgust
- Other negative feelings
The dream content most often involves great danger that comes upon the person dreaming. It may also focus on other distressing themes. You can normally recall very clearly the details of the nightmare when you wake up.
A disturbing dream that does not wake you up is not considered a nightmare. It is simply a “bad” dream. You may have more than one nightmare in a night. The content of these dreams can often have the same theme.
Nightmares tend to occur during rapid-eye-movement (REM) sleep. There are five stages of sleep that make up one sleep cycle. You normally complete four to six sleep cycles in one night. The fifth stage of each cycle is called REM sleep. With normal sleep patterns, people cycle though the five sleep stages about every 90 minutes. REM sleep makes up about 20-25% of your total sleep time.
The first REM period tends to last for only a few minutes. The REM stage gets longer during each sleep cycle. Your last period of REM sleep may last as long as an hour. This means that nightmares are more likely to occur in the last third of the night.
Nightmares that arise due to a trauma can also occur in earlier, non-REM stages of sleep. They may depict some of the events from the trauma. They may even replay the event in the dreamer’s mind.
Nightmare disorder can be confused with sleep terrors or REM sleep behavior disorder (RBD). A person having a sleep terror often screams, kicks, thrashes and even bolts out of bed. He can be very hard to wake up. When he does, he is very confused. He only recalls fragments of a dream. Sleep terrors tend to occur in the first third of the night. RBD involves a person acting out his dream. It can even result in physical injury. It is most common in middle-aged men.