Our 16 month old only naps occasionally and has to be in the carrier on the bus or in the car. It's been like this since around the time he turned 1. As long as he had these naps before 3 he would go to bed between 6:30-8pm.
Since Christmas it doesn't matter whether he naps or not or when he naps. He will be up until 10/11 every night. Sometimes he seems tired and sometimes full of energy. Nothing works/makes a difference.
He got a new tooth a couple of days ago and seems to be experiencing a bit of separation anxiety but other than that I can't think of anything else that has changed. He has very active days with 1-2 toddler classes except for Sundays and he has loads of things to do and play with at home.
He is also waking up multiple times a night to breastfeed which he didn't really do before.
We cosleep so he is still in our room. He breastfeeds and cuddles to sleep but he now just screams and trys to get off the bed if he's decided he's not ready to go to sleep.
He is sleeping in later in the morning too so he must be tired.