We’ve had some sleep issues and we had to use sleep training. We didn’t go full “cry it out”, but they have to get used to falling asleep by themselves. As long as someone is there, they’ll continue to be stimulated because they want to play, cuddle, and have fun. It wasn’t easy, but the lack of sleep was killing us. It’s feels pretty rough during their “learning phase”, but looking back after 8 years, it was the right choice.