In Reply to: Let your hair down posted by Victoria S Dennis on November 20, 2008 at 17:02:
: : : Whats the origin of idiomatic expression of 'let your hair down'?
: : My guess -- grown women used to wear their hair up in a bun or whatever. Hair was only "let down" at night or when they were going to wash it.
: Close. The point of the idiom is that it was improper for a grown woman to appear in public with her hair loose, so she could only let her hair down in an informal situation when only family or intimate friends were present. A young man might ask his fiancee if he could see her with her hair down - that was quite a sexy request, which he couldn't decently make before they were engaged. (VSD)
Which gives us the idiom, to let your hair down, that is, allow yourself to be perceived as you really are, to reveal yourself more intimately than the usual public self, to behave informally.