The philology of sleep

I've had a series of dreams lately -- well, not dreams exactly, but liminal events at the moment of waking -- in which I see an OED search results screen (new format) that has a series of entries like "six hours three minutes," "six hours four minutes," etc., and apparently a definition for each, but I'm always fully awake before I can click on any of the definitions. The interpretation is fairly obvious, but I am a little intrigued by the notion of tabulating the precise differences between the various kinds of sleep -- for a borderline insomniac like me, it's rare for two nights' sleep to be identical, but maybe there are only seven kinds rather than infinitely many?

In other sleep-related news, I was reading Jonson's Epicene (which strangely I'd never read before -- I'm a huge Jonson fan -- E is not my favorite Jonson play, but is the one closest to Restoration comedy and I'm not surprised that Dryden chose it as his model for close reading) and was amused by this bit:

MOR: No, I should do well enough, if you could sleep. Have I no
friend that will make her drunk? or give her a little laudanum?
or opium?
TRUE: Why, sir, she talks ten times worse in her sleep.
MOR: How!
CLER: Do you not know that, sir? never ceases all night.
TRUE: And snores like a porpoise.

Why does it make sense to accuse someone of snoring like a porpoise? Snoutedness, of course! The only time people sound dolphin-like in their sleep is when they have a cold and their breathing is a polyphonic whistle.