Regression

Not formula related, but does anyone know about the 4 month regression and sleep association? I know they said that this is when they realize what is expected when they are put to sleep, is that just for night time sleep or also naps? We will probably sleep train when this happens but he is still in his swing for some naps because he hates the crib for naps and I dont want him to think the swinging will always happen for naps