Exploding head syndrome is more common in women than men, and people with the disorder are usually in their 50s or older. Once a person has had an incident, sometimes called an auditory sleep start, he or she may not experience one again for long periods of time, if at all.

What’s unusual about the disturbance is it’s only heard inside the mind. It has been compared to thunder or an explosion that lasts just moments before the person wakes up. Episode-induced anxiety sometimes causes heavy breathing, rapid heartbeat and cold sweats.

Exploding head syndrome doesn’t cause swelling or damage, but on occasion the episode may be described as a headache. In some instances, people with the disorder may also see flashes of light. This is called a visual sleep start.

According to the American Sleep Association (ASA), the disorder has been linked with stress and fatigue. Episodes often come in clusters and are relatively erratic.

The ASA does caution people who think they might have the disorder to speak with their doctors. Similar experiences may be the result of medication or other conditions. Distress over episodes also could lead to insomnia.

Although the exact cause isn’t known, the ASA says that a regular sleep routine and calming activities before bed may help prevent incidents.