You’re Not Alone (va io9): ‘New findings indicate nearly one in five college-age students has been startled awake by an abrupt, loud noise that doesn’t actually exist. Known as “exploding head syndrome,” the psychological condition appears to be more common and disruptive than previously thought.

Some of you may already be familiar with exploding head syndrome (EHS). I know I’ve experienced this on at least one or two occasions, and it’s not pleasant. It’s characterized by an exceptionally loud noise in the head (sometimes described as “an explosion” in the head), usually during sleep-to-wake or wake-to-sleep transitions. Though benign, it can be extremely stressful.

Here’s what Washington State University psychologist Brian Sharpless, a sleep disorder expert and lead author of a recent study study on the prevalence of EHS among college undergraduates, told me about the condition:

Exploding head syndrome episodes by themselves are harmless. They can cause problems with a relatively small number of people if episodes happen too frequently, regularly disturb sleep, or if people react to them in unhealthy ways (e.g., by becoming really anxious before bedtime or fearing that something more serious may be wrong with them).’