2yo suddenly started waking at 5something-am for past 5 days - HELP

[oysterpots]

My son turned 2 last weekend and since Thursday has woken before six every day, usually more like half 5. Before this he slept till at least 6.30-7am consistently.

He has a nap every day, normally 1-2.30/3ish, goes up for a bath around 7pm, in cot by 7.30ish but often doesn't actually settle until 8 or 8.30pm (but self-settles).

So total sleep for a normal day is between 12-13 hours. At the moment he's getting 11 or so.

I think he's tired, and it feels like the more tired he's getting, the more restless he is.

What can I do? Other than go to bed at 9pm, which quite frankly I find a bit soul-destroying!