Exploding head syndrome sounds like something you call your worst headaches, but it's a real condition.
People who have it hear the loud sound of an object crashing to the ground, or a bright flash of light when they're falling asleep, even though those things didn't actually happen.
Now a new study in the journal Cephalalgia is exploring the condition further by interviewing people who have it.
Part of the process of falling asleep involves shutting down the auditory neurons responsible for hearing. Scientists think when someone has exploding head syndrome, instead of the neurons shutting down, something causes them to fire at once, leading to phantom loud noises.