To relax; to be unhibited

Come on Professor Jordan, school's over! Let your hair down for once and let's have fun all together

Suvvia Professor Jordan, la scuola è finita! Per una volta si lasci andare e venga a divertirsi con noi

Mr. President, when asked how did he manage a family in the White House, answered: "We're trying to strike a balance. You still want family time, when you can really let your hair down"

Il Presidente, alla domanda su come potesse gestire una famiglia alla Casa Bianca, rispose: "Cerchiamo di trovare un equilibrio. Si ha comunque bisogno di passare del tempo in famiglia, dove ci si può veramente lasciar andare"

Until fairly recently, a woman was expected to maintain a very formal public image, and as a result, often wore her hair pinned up on the top of her head. Only in the privacy of her home (or even better, her bedroom), she would feel free to relax and would let her hair down