May 01, 2018

What causes one to be startled awake by a noise no one can hear?

Q: A couple of times in the past months, my wife has woken in a panic saying she heard a loud noise like a crash. There was no noise, and she assumes it was a dream. Is this something to be concerned about?

A: It's hard to say without a medical evaluation, but you may be describing a poorly understood phenomenon called exploding head syndrome. Those who experience it report being startled awake by what's often described as a loud, sharp noise such as the crack of a whip, an explosion, a gunshot, a lightning crack, a metallic crashing noise, an electrical noise or other sounds. Some people may also experience flashes of light, mild pain, sweating or a racing heart rate.

It's not known what causes this sensation, but it's believed to occur as your brain is transitioning from wakefulness to sleep. It's thought to be similar to the common phenomenon of jerking awake as you fall asleep.

Some people have one event in a lifetime. Others have several a night. Episodes may occur on a consistent basis, or come and go. It's estimated to occur at least once in about 10 percent of the population. It appears to be more common in women and older adults.

Exploding head syndrome doesn't appear to cause direct physical harm. The main complication is fright and distress in those who have it, either because they fear a serious disease or because sleep is disrupted.

Diagnosis involves ruling out other possibilities, including a stroke. These possibilities can usually be distinguished quite easily. For example:

  • Strokes usually have one-sided symptoms
  • Headaches are usually more painful and the pain lasts longer
  • Night seizures usually aren't remembered
  • Panic attacks aren't usually accompanied by a loud noise

Reassurance and education on the phenomenon are often the only treatment needed. Additional treatment steps aren't well-studied, but...