We are going through the same right now. Our daughter 17 mon. Has done this twice (lasting around 7-10 days.) Once at 15 months when she got the flu shot and now she has a cold/terrible cough which is waking her at night. The ped says she just isn't feeling well and deserves the extra attention. We also tried the "cry it out" to no avail. She would either scream at bedtime for two hours while we did everything we knew how and were in and out of her room several times or she would fall asleep but wake up for several hours in the night. I do not think that your daughter is hungry, babies of this age should be able to sleep through the night with no need for food, formula or otherwise. In our case our daughter seems to do this when she isn't feeling well, but it also could be teething, separation anxiety, or nightmares. If she isn't feeling well... we have done everything to address our daughters cold, cough syrup, vick's, humidifier, ect... Beyond that all we can do is comfort her. Which we did but she wouldn't let us put her in bed or leave her room after two hours in the middle of the night and against my better judgement I brought her into our bed. She feel right to sleep, and the better for all of us. The ped. says give it five to seven days, once the cough is gone, then she needs to get back to self-soothing if she wakes at night (Which she is good at normally, no sleep issues aside from these instances.) Have you tried motrin, in case it is teething. Teething is most painful before we ever "see" any sign of teeth. So it is hard to rule that out. Try motrin/tylenol and see if you notice a change. I also talked to our ped about when they refuse to sleep, when you do go in they smile, stop crying, want to play... You know. When this is the case, and I can tell b/c she isn't sick, and she will start talking to me when I open the door, I go in DO NOT pick her up, hug, say firmly "It is bedtime, mommy is right outside the door, I love you (or something similar, but keep it short, just to reassure her that you are there)" lay her back down, tuck in, paci... and walk back out. Less than a minute. The ped says do this over and over, first wait five minutes before going back do this a few times then wait ten minutes a few times then fifteen. If this does not work you can do what I have seen on SuperNanny. Put the baby in bed, crying/upset, do not talk or take the baby out of her bed. Stay in the room with your back to the crib. Baby can see you, know you are there, ect... You will have to listen to them scream for you and reach for you. I am skeptical of this b/c if they do fall asleep but wake later and you are no longer there wouldn't they be even more upset. Thinking mommy leaves me. Ask others about this technique. I have also read from other moms that they placed a mobil back into the crib to help soothe baby back to sleep. I just unpacked our old cribside mobile. We will see how it works. If she wakes up scarred she will be able to turn on the music. I think that once you have exhausted all possibilities then the best thing for everyone would be to give in for the time being. This will pass, for now everyones comfort is at stake. We are going to give it 5-7 days as the ped recommended then she will have to figure out that it is time to fall asleep or fall back to sleep on her own. These things usually happen during a transition for them, when they change and grow. It will pass. As my ped said "suck it up."