If there's one thing worse than a nightmare, it's being woken up from one by something leaping onto your chest out of the pitch darkness.
How did next-door's cat get into the house, anyway? That's what I want to know.
And if there's one thing worse than that, it's waking up from a nightmare to find a cold hand clutching your throat.
Still, it's almost worth it for the relief of discovering the hand is actually your own.
Nightmare. There's a story that this word comes from the habit of taxi-drivers of using their most broken-down old horses (female horses are of course mares) during the night shift where they couldn't be seen very well.
Actually it's from night, meaning, guess what, night, plus mare, evil spirit. There are similar words in Old Norse and Polish. The Polish one begins rather pleasingly with a z: zmora.
Nightmares also used to be evil spirits which bothered or suffocated sleeping people, but luckily these have all now become completely extinct.