Ren - DS would often cry and struggle (I mean A LOT) when we first put him in the HAB, but a bit of jiggling and he'd drift off to sleep after a little while (usually). You can't force them to sleep, but sometimes you can help them along... Another thing that sometimes worked at that age was to drape a light wrap over his head so he couldn't look around. sounds cruel, but it did work.

His sleeps got a lot better (day and night) with help from the no-cry sleep solution, though it only lasted for a short while before *something* changed and we had to figure out a whole new strategy.