sleepovers

What do the following expressions have in common?

• sleepover
• slumber party
• pajama party

Yeah, right, they all refer to the same kind of thing. But look more closely--what else do they have in common? OK, I'll tell you. They are all American ways of describing the same thing--all of which are known in BrE, but used to lesser or greater degrees. 

Of course, the last one  is pyjama party in BrE, but don't let the spelling fool you. While/whilst pyjama party is not marked as having American origin in the OED, this Google ngram tells the story: first there was pajama party (blue line), then there was pyjama party:
 

Slumber party is very American, and I can't say I've ever heard a BrE speaker use it, but it's something they know from American films and books.

So, my question to my English friends was: if all these things are AmE, what did you call it when you were a kid? Their answer: they didn't have a noun for it. They'd sleep at their friends house, sure, but they'd just stay the night or stay over at Jen's. All verbs, no nouns. My friends also told me that they thought of the noun-described things as 'very American', 'the stuff of American books'. But don't let the lack of nouns make you think that British sleeping-over was just, you know, sleeping without the rituals of a nounified event. My friends all insist that staying at a friend's had to involve a midnight feast (which might be as early as 9:00). The OED defines this as:

n. a feast or snack at midnight; spec. a night-time feast held by children in their bedroom or dormitory, usually without the knowledge of their parents, teachers, etc.

I'd heard this phrase before in Charlie and Lola, but hadn't reali{s/z}ed what an institution they are. For a hint of how much of an institution, see this Guardian Word of Mouth blog about it. My friends attributed their knowledge of midnight feasts to Enid Blyton, but she certainly didn't invent the idea.

These days, the OED marks sleep-over (as they spell it) as 'chiefly U.S.', but my friends and their children use it liberally (though, it must be said, it so happens that many of Grover's little friends have a North American parent, so my sample is probably biased). Grover (who started big-kid school this week--it's a year earlier in UK than US) is absolutely obsessed with the notion (stress: the notion) of having a sleepover with her friends. Her favo(u)rite game with her friends has been, from an early age, 'going to bed'. Let me tell you, if you're going to have a small child at a late age, get one who likes to play bed-based games like 'going to sleep', 'bear cave', 'moles in holes', and 'driving a car' (just be sure that you're in the 'back seat', where the pillows and headboard are). Just come up with lines like 'my eyes are closed because I'm a blind mole' or 'the wind is in my face', and you're guaranteed late mornings in bed. 

Before I go, a note to readers nearby. I'm giving my talk 'How Americans saved the English Language' in a couple of places soon:

• Thurs, 27 Sept, 4:00pm at Sussex University English Colloquium, Jubilee Building G08
• Tues, 8 Oct, 8:00pm at Brighton Skeptics in the Pub, Caroline of Brunswick Pub. Details here.