My seven-month-old was sick and spent a week in our bed because it was the only way he’d sleep. Now that he’s back to healthy, he won’t sleep in his crib. Did we screw ourselves? Is co-sleep habit-forming?—Tired
All sleep behaviors are habit-forming, I am somewhat sorry to say. And kids are really, really responsive. Part of the reason why sleep training often works so quickly is that they are adaptable and can learn fast. But these skills can also be unlearned fast, which is what you are seeing here. What you did makes a ton of sense — sleeping when sick is so important — but it’s not surprising that now he doesn’t want to go back.
Moving forward … the first question I would ask (I think I know the answer but will ask anyway): do you want to go back? Some people like co-sleeping, and, with an older infant, the risks associated with it (if you do it safely) are much more limited. If co-sleeping is what you want in the long term, maybe there is no problem.
Your sign-off makes me think that’s not where you want to be.
If that’s the case, then there is a glass-half-empty and glass-half-full answer. The glass-half-empty answer is that the only way to get back to where you were before is to enforce it consistently, which probably means some crying. You can read this post on sleep training if you want details on how others have done this.
The glass-half-full is that you can see how fast one habit developed, and the other can develop fast too. You’re not many days out of fixing this, just as it wasn’t many days to get into it in the first place.