Hi,
Just wondering what you think about this being developmental? DS went through a stage where he became more aware of his dreams and they scared him witless - he did not want to go to sleep because often the same scary dream would start up again, hence the long waking when in reality, he is tired. Can be worth checking temperature - even slightly overheated kiddies have these more often. OT also makes it worse.
It really helped for us to talk through his day before bed. Basically I just talked through all the things he'd done in the day, mundane or exciting and it seemed to allow him to just settle any thoughts or feelings he might have had (without necessarily expressing them, particularly initially) and he tended to sleep better.
Do you darken the room for naps? Is it an issue with darkness? Often not an issue at this age per se but it can be a signal to him that scary dreams could be coming, if the dreams are happening more at night.
Definitely worth trying that earlier BT if he's looking tired, IMO.