Nightmare is classified under the category of sleep disorder also known as parasomnias in DSM 5 classification of psychiatric disorders. Nightmare is an experience of bad dream during the sleep which involves a variety of emotions like fear, anxiety, dysphonia, sadness, anger, etc. It can also characterized by threat to life, safety, fear of losing someone dear, disruption of physical integrity, etc.[1]
Nightmare is more commonly seen among children and adolescent age group in comparison to the adults with almost three-quarters of children have experienced them at least once in their lifetime. Usually the onset of this disorder is between 3 to 6 years and the peak incidence is found in the age group of 7 to 9 years. Nearly 35 to 45% of children between 2 to 18 years suffer from sleep disorders which also include nightmares as the commonest of them all. Different data statistics have suggested different incidence of nightmares among different age groups and it also varies because of different criteria for classification of nightmares and different population.
How Many People Have Nightmare Disorders?
It has been calculated by epidemiological studies that the prevalence of nightmares is 2 to 11% among the young children are associated with high frequency and consistency whereas 15 to 31% of children in younger age group experience nightmares frequently but not have much consistency. As the age group is made narrower between 3 to 6 years, various studies even suggest that the number of children experiencing nightmares reaches to as high as 50% with disturbing both parent’s and children’s sleep. The children who have experienced nightmares consistently during their childhood are nearly 33% liable to carry forward this sleep disorder in their adulthood as the retrograde studies show that the adults suffering from this disorder have a past history of consistently encountering nightmares in their young age in about one-third of cases. Nonetheless, the exact data accumulation is not possible due to subjective variation and younger age group because children are not able to tell about the disorder many times.
The racial and ethnic variation associated with nightmare disorder is not encountered and it is found equally in all races and ethnicities. Variation of prevalence among different success is not found in the younger age group with males and females affected equally but in adolescence and adulthood it has been derived that the nightmare disorder is more commonly found in females which may also be attributed to more reporting tendency in females than in males. The cause for nightmare has been attributed to lesser neurological maturation which improves with age and also explains the decrease in incidence with age.
Is Nightmare Disorder Hereditary?
Although the nightmare disorder is not found to be strongly associated with genetic and heredity causes according to a study about 7% of the children suffering from this disorder are found to have a family history of nightmare and other sleep disorders.[2] Also, the causes for this disorder like depression, intellectual disability, mental retardation, organic brain diseases, etc. are found to be more commonly linked with genetics and have a hereditary course which could make it an association with genetic causation. But there has been no direct genetic cause found for the nightmare disorder and hereditary inheritance is also so uncommon.
Conclusion
Nightmare disorder is a commonly found sleep disorder with a high incidence and prevalence in early age group. The adults suffering from this disorder usually have a past history of nightmares in their childhood and the adult onset of this disorder is rare but associated with psychological factors like stress, anxiety, depression, etc. It is usually associated with other features like dreaming, hypersomnolence, sleep paralysis, hallucinations, cataplexy, etc.
Although many cases have been reported with the evidence of the past history of the disorder in previous generations or in the same generation among siblings no direct genetic or hereditary cause has been described.
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