Hello My DS2 is now 6 months and I am introd...

Hello My DS2 is now 6 months and I am introducing solids which he does enjoy, however I did a wee trial and when he has solids at 11am and 5pm he wakes at around 2-3am wide awake!! When I have a just a bottle day he sleeps right through..? Does anyone know why that is or have u experienced this at all? Thanks