hi there
heres some stuff that i learnt about sleep
diet plays an important role. your child needs enough protein and your childs iron levels must be right.
your childs routine must be as predictable as possible say an hour before nap or sleep.try playing a song your child likes thats soothing. also try and swing your child in a swing or rocker for minumum 10 minutes as that helps them fall asleep later. not sure why but if your baby sleeps at 7 then try the swinging at 5.
keep to bath time routines and especially with 2yr olds, they need their routine predictable and rigid. if you want to be more extreme then you are going to have to sleep train.
hope this helps.
teething can upset sleep like my son at the moment. his molars are coming out so he is not sleeping well at the moment.