I was looking up a different word in my Oxford Russian-English dictionary when I happened to notice the phrase sonnaya arteriya, defined as ‘carotid artery.’ Now, sonnyy means ‘sleepy,’ so sonnaya arteriya literally means ‘sleepy artery,’ and this suggested that carotid (a word whose etymology I don’t think I’d ever investigated) had something to do with sleepiness. Sure enough, it turns out it’s “ad. Gr. καρωτίδ-ες, f. καρούν ‘to plunge into deep sleep, to stupefy’, because compression of these arteries is said to produce carus or stupor. (Galen.)” (OED). The AHD takes it back to Indo-European *ker- ‘head’ (“to feel heavy-headed”), but that may be pushing it. At any rate, I like the plain-spoken Russian phrase better than the opaque English one.