It doesn't matter if you can do a photography shoot for five or six hours at a time, if the baby becomes fussy or upset with what is going on, take a break, or wait until the next day. Bright lights, strange objects, and people shuffling around them are likely to make them a bit irritated or nervous, which doesn't translate well in photographs, and it isn't doing your baby any favors either. Watch the babies cues to see if they're hungry, need a diaper change, sleepy, or if they're just annoyed with the situation, and fix accordingly. After all, when working with such tiny models, you'll quickly learn that you're not the one calling the shots!