Nightmares that occur frequently are a parasomnia dream state event, in which visual sequences unfold that often depict imagery or situations that are particularly disturbing or frightening to the individual experiencing them, and may often come from fears in their own subconscious.
Nightmares are considered a sleeping disorder when they occur frequently enough that they disrupt sleep on a regular basis, and may cause the subject further fear of sleeping, which can lead to sleep deprivation and the formation of other sleeping disorders or medical or psychological conditions.
Nightmares are different from sleep terrors in that they are similar to a regular dream involving images and sound, but the images often invoke fear or anxiety in the subject. Sleep terrors contain no imagery or sound, just an overwhelming sense of unshakable fear, and may also be accompanied by temporary sleep paralysis. Nightmares are only considered as such when they cause an immediate awakening from sleep, which usually occurs at the climax, or extreme point of terror of the nightmare. Other instances of scary dreams that may be recalled, but did not cause awakenings are just considered bad dreams. Nightmares are often vividly recalled, and the sense of fear felt during them may continue for some time even after waking. Nightmares may also lead to bedwetting in people prone to bedwetting, though the statistics for this are not known with certainty.
Nightmares are extremely common, and may affect as many as 80-90% of people at some point in their lives. Nightmares can begin as early as age 3, and are common in young children. They generally lessen as a person grows up, but most adults will also have nightmares on occasion during their lives. They are common in both males and females.
Some of these cases can be caused by medication use, or by extreme levels of anxiety in everyday life. There is also a slight increase in the chances of having nightmares as a sleeping disorder if someone in your family has a similar problem. Sleep deprivation may also be a cause of nightmares, but whether this could lead to chronic nightmares is unverified.
Nightmares are most typically treated by doctors or therapists, and not sleep doctors, as they are rarely related to any other sleeping disorders, and are not corrected through any changes in sleep hygiene. Nightmares will most often be caused by mental disturbances, sleep deprivation, or may have no identifiable cause. Most often chronic nightmares are caused by psychological issues though, and for this a psychologist or therapist should be consulted. Counselling or psychotherapy are effective treatments for resolving the issues that are likely causing the nightmares. Nightmares that often recall a particular traumatic event or person that causes the person stress may require more intensive therapy. Hypnosis has also been cited to have uses in the field of dealing with dreams or nightmares, though conclusive statistics on this do not exist. Medications may also be used. Uses for medications in relation to nightmares include preventing time spent in deep sleep where nightmares are most likely to begin, though this approach is considered controversial, as deep sleep is considered much more important than reducing the occurrence of nightmares. Another approach of medications is to reduce the amount of awakenings caused by nightmares.