Thumb v. binky

We've been caught up this past week in a major struggle that Ellie is having.
I wrote some time ago about her love of her thumb, but she lost it a couple weeks back. We're not sure why, but think it has to do with using a pacifier (binky) during her days at school. Whatever the cause, Ellie lost her instinct to suck her thumb... and thus, lost her key method of soothing herself in the middle of the night.
This has meant some long nights for all of us.
One night last week we got Ellie to bed at 8 p.m., she woke up at 10 pm and again at 1 am and then again at 4 am! This was one of the nights when Brian was really sick, so I was the only one responding. The next morning was not a cheerful one in our house.
We didn't realize what the problem was until Friday night when I thought to give Ellie her binky. I gave it to her around 2 a.m. and she was thrilled... until 2:15 a.m. when she dropped it from her mouth. Four trips to her room and one hour later, I decided that the binky at night was NOT going to work for Ellie.
So we made the tough decision on Saturday to start some sleep training for Ellie. The book we have suggests doing it between four and six months of age, and Ellie is 16 weeks (turning four months next week). The technique we decided on is called the Ferber Method.
Here's how it works:
When Ellie wakes up in the middle of the night, as long as it hasn't been more than four or five hours (so we know she's not hungry), we let her cry for a few minutes.
We then go into her room but don't pick her up. We can stand by her crib and stroke her chest or face, tell her that we love her and are there for her. We're only supposed to stay in about a minute and then say, "We love you. Good night. Sweet dreams" and leave.
Then we have to wait five minutes before going back in.
After the next visit we have to wait 10 minutes. Then we wait 15 minutes, and so on.

This is SOOO much harder than I ever thought it would be. It's painful to listen to Ellie cry for so long and not go in to pick her up and soothe her. But this way we're supposed to be teaching her to soothe herself. And it does seem to be working.
The first night we did it there were two wakeful periods of Ellie screaming for about 15-20 minutes. The next night it was more like 10 minutes each time. And last night Ellie woke up once and was back to sleep after crying for only about five minutes.

I have to keep reminding myself that we're doing it for her own good — and for our own sanity, so we can be good parents. But the first night we did it, Brian and I were laying in bed holding each other because we were so upset hearing her sad, exhausted cries.
We've seen Ellie re-discovering her thumb a few times now. So hopefully the nights continue to get a little easier. And, in the meantime, we've told the daycare workers that her binky is off limits!