Hmmmm, it has a name. I can add this to the list of my syndromes. It's not a joke; you can Google for it, and read about it. Of course, my head doesn't really explode, but it does sound like it sometimes, and it gives me quite a jolt. It interferes with sleep. It appears this is a syndrome, and no one knows for sure what causes it.
The first time it happened I was in the car with all my family - six of us on vacation. I must have begun to be drowsy. I heard a sudden huge bang! that sounded like a shotgun fired inside the car close range. I asked, "What was that!!!" "What was what?", the others asked. No one else heard the unnerving blast; I was glad I was not the one driving.
I have a sleep disorder, and with this in addition, I'm frequently grumpy mornings, because the noises happen when I am falling asleep. Of course, I jump nearly off the bed, nerves Zinging, heart pounding wildly. Recently, I thought a light bulb had popped. It sounded just like one had popped loudly, but when I asked my husband about it, he hadn't heard anything.
During hot weather this past summer, my garden helpers and I started our workdays at 7:00 A.M. My personal morning routine takes me two hours, so I had to rise at 5:00 A.M. to get everything done. By lunchtime everyone was gone, so I usually took a nap down in our cool basement-level family room. One day just as I fell asleep, a loud sound startled me, I jumped, my heart pounded, etc. It sounded like an old-timey tin penny-whistle given one loud blast. I calmed down and was going back to sleep - it did it again! - this time waking me a bit more. I thought maybe I could still get to sleep, so I tried... it happened again! I was so angry I just gave up and got up.
Those few are the sounds I am able to describe. I don't know how to describe most of the sounds that happen. But, they are loud and keep me awake. It can take me as long as five hours to get to sleep. Due to the fact that I have a terrible time getting to sleep, I am not a happy camper if anyone, or thing, makes a sound that wakes me before I have slept enough - because it is almost impossible to get back to sleep. The alarm clock is not my friend! I am sorry to learn that other people are cursed with this "thing", too. Hope it isn't you, or is it?