All of a sudden, my exclusively breast fed 4.5 month old DD has upped her nightly feeds from 1 to 2 every night. I used to get nice 7 hour stints followed by a 3-5 hour stint. Now it's 4.5 hours max and 2 quite regular within 1hr +/- feeds. A friend says maybe I have a low supply at night. If so, why would that happen suddenly and what can I do about it?