So I pulled "The Bread Bible" by Rose Levy Beranbaum: Copyright 2003 (Pg 30 paragraph 4) - It's been a while since I had to properly cite so forgive me
"When chilled, the yeast goes into dormancy, slowing it's activity and producing more alcohol (Me: producing more alcohol doesn't sound right, but that's what it says). This decreased activity gives the bacteria a chance to feed on the sugar, develop more, and produce more acetic acid. Temperatures of 40 to 55 F are ideal for the formation of acetic acid; 55 to 90 F results in the formation of the blander lactic acid. Acetic acid imparts a far more sour quality to bread than lactic acid. As an added benefit, acetic acid also strengthens the doughs structure, although too much of this acidity would ultimately weaken it. Some bakers prefer the milder flavor provided by lactic acid."
..... paragraph 5 .....
".... if the dough ferments for too long, the yeast and bacteria will consume all of the sugar in the flour, and the bread will have a pale crust and bland flavor. Some residual sugar in the dough is necessary both for flavor and to brown the crust."
Jeffery Hamelman's "BREAD" will tell you the same thing
By the way, both great books to get to know your dough