May baby is 11 months old he also usually wakes up at 4am..i think they are very excited to play and get out.
Try not to over excited the baby before the sleep. Try to read bedtime stories.
Sometime teething also affecting cos their gum feel pain
My baby does same. I change her diaper and breastfeed her to calm down
Try to shift his day time napping time and hour...it wrks for mine..
Same for my baby. End up feeding her comfort milk to sleep.
Is it because he does not have enough nap in the day??
Either play too much during the day or teething.
Could be teething or night terrors
my baby also hve this prob..