The primary causes of nightmares are trauma, stress and major life events. Other contributing factors include substance abuse or withdrawal, medications, scary stories, sleep deprivation, fever-inducing illnesses and certain psychological disorders. Sometimes nightmares are idiopathic, meaning that there is no discernible cause.
Medical and mental health professionals consider nightmares to be normal human functions. Nightmares primarily occur in children under the age of 13. As children age, their frightening dreams begin gradually decreasing, and as of 2014, researchers are unsure why. Any event that induces a great deal of mental, emotional or physical stress in either adults or children can lead to nightmares for a short time.
Recurrent nightmares that make people fear sleeping, disrupt normal sleep schedules or alter daytime behavior may indicate sleep apnea, post-traumatic stress disorder, anxiety, depression or sleep disorders, such as night terrors.