Turn in

What is the origin of the phrase 'turn in'? As in..
'I am tired so I am going to turn in'

In the meaning of "go to bed," the Oxford English Dictionary describes this as a colloquial term of nautical origin. It appears to have been well-known in this sense in the 17th century, and from the 19th century the OED gives us this example:

1837 T. HOOK Jack Brag xiii, Jack 'turned in', as the sailors say.

Perhaps someone can say why sailors used the term.
SS

Because sailors' quarters were so cramped that there wasn't room to sit on a bunk before lying down? ~rb

Sailors didn't have bunks in the 1830s; they had hammocks. And you have to execute a kind of wriggle to get in or out of one of those, so "turn in" is quite accurately descriptive.

Than again, there's the phrase "turn out" as in "turn out the guard", which I believe is much older, and I think is a metaphor for emptying something out (e.g. "turn out your pockets"). It could be that "turn in" is just a back-formation from this. (VSD)