I won't give any suggestions because there may be variables that are not mentioned in the OP. Would suggest one thing though, search for Matthew Walker on YouTube. He wrote the book 'Why We Sleep'. He has a lab at UC Berkeley. In short youtube video snippets, he has explained a lot of things on how our behavior (including what we eat, when we eat, how we eat, etc) affects sleep. Hopefully, you will find your answer there. There is never 'one size fits all' answer when it comes to sleep, because of the complexity in the sleep process.
Somebody mentioned sleep apnea, look into that too.