Most people experience a nightmare from time to time, such as running late, being naked in public, or being chased by a supernatural threat. On average, we go through four or five dream cycles per night, each lasting between 15 and 40 minutes. Typically, these dreams—whether pleasant or disturbing—are forgotten shortly after waking.
Many classic nightmares, like falling or losing teeth, are simply the mind processing real-life issues such as insecurity or fear of losing sexual potency, and are generally nothing to worry about.
When Nightmares Become a Concern
Science communicator Jorge Alcalde says that recurring nightmares could be a cause for concern. Speaking on Spanish radio show Herrera en COPE, he explained: "A person who feels overwhelmed by frequent nightmares should report them, because it might indicate an underlying emotional issue, anxiety, stress, or depression."
Dr. Abidemi Otaiku, Clinical Research Fellow at the UK Dementia Research Institute, presented findings at the 2025 European Academy of Neurology Congress. In what he described as the first major study of its kind, his team found that adults who suffer weekly nightmares are more than three times as likely to die before age 75 compared to those who rarely or never have bad dreams.
Links to PTSD, Depression, and Heart Disease
Recurring nightmares have been linked to post-traumatic stress disorder (PTSD), with 80% of PTSD sufferers reporting them. They are also strongly associated with depression and anxiety disorders. Additionally, frequent nightmares can indicate heart disease, as they may cause waking with a racing heart and high blood pressure. They have also been connected to sleep apnea, where the brain may experience nightmares of choking or drowning due to restricted oxygen.
Other sleep disturbances, such as sleepwalking and restless leg syndrome, can also signal underlying issues, Alcalde warns. One extreme disturbance is sleep paralysis, where a person wakes before the temporary paralysis of REM sleep fades. This can cause terrifying hallucinations, often interpreted as hauntings or alien abductions.
Neurological Links Under Investigation
The connection between parasomnias (sleep disorders) and neurological conditions like Parkinson's and Alzheimer's is a major focus of medical research. The debate centers on whether parasomnias are a cause or consequence of these diseases. "It is known, for example, that Parkinson's increases the likelihood of unusual behaviours during sleep," Alcalde said.
He stressed that occasional nightmares are not a cause for alarm and that he does not want to worry hypochondriacs. Unlike a blood test, there is no scientific certainty that occasional sleep disturbances have an explicit link to disease. "Nightmares are not a symptom of illness," he emphasised, but they are a possible sign that something in one's emotional state could be improved.
