18 month old has been sleeping through the night since 12 months. Put down awake for bed and naps. Did not do CIO, did gentle sleep/Pantley shush pat sorts of things.
For last month or so LO has been waking at 5 am. We have gotten an extra layer of blackout curtain (so two layers total!) and run a white noise machine throughout the night. Sleeps in sleeping bag (tog adjusted according to room temp).
Routine is this:
Wake up at 5/5:15 
Nap 11:30/12 - if down at 11:30, will wake up 1.5 hours later. If down at 12 or after, will sleep 2+ hours (I suspect overtired and natura rhythm seems to be to want to sleep at 11:30?)
Bedtime 6:30/7. Sometimes chatters in cot for a solid 30-45 minutes. Sleeps through until 5ish.
Is my baby just a lark? Or can we adjust something so that wake up time is at least 6/630? I’m knackered. I suspect that longer naps may correlate with earlier wake up but have been using an app and it seems not to actually matter 
Any thoughts or help? TIA xx