5months usually a good sleeper but now wakes up often at night

Hi all! My LO has just started solids, the first few days was a heaven.. she slept overnight and by overnight i meant 6:30pm until 2-3am..and usually sleeps right after a bottle.. but now she wakes up at midnight just chatting away, given her a bottle to settle her to sleep and then she wakes up 4 hours after.. anyone with similar situation? Any tips on how to keep them sleeping a bit longer? Or is it a sleep regression?