More than a few summers ago when as an ordinary seaman with skin like the lee side of a peach I too referred to it as the last dog watch. If you kept the middle watch you didn’t turn to at 06:00 to holy stone the decks but stirred from your hammock at 06:30.
If you haven’t read Dana’s book do so. I’m of an age where many in the merchant marine had sailed in very poor conditions and TB was prevalent. The Port Alfred was the last ship I knew where ratings were in the forecastle.