hi,
Jake does this sort of thing, except he saves his high pitched scream for 4 am!
I have consulted my BW book, and have transitioned Jake onto a 4 hr E.A.S.Y, which extends their awake time, and therefore their naps too.
This has been working a treat to extend naps, where mostly he is quiet(although its all gone wrong today!)
You may have already done this as you LO is older than mine, but thought it was worth saying.