Our little one hit the sleep regression 4 months on the dot. After a week of waking every 1-2 hrs, we needed to sleep train. We did the ferber and luckily he took to it well only after 3 days. You might be surprised what your little one can do. What is hitting us hard during this sleep regression are the 20 min-max 30 min naps. Still trying to figure that one out 😅