8 month old has gotten into the habit of waking up at 1

Jackie

Wakes up at 1am and stays up till 4ish

She falls asleep in my arms .. i go to put her down and she cries.

Ive left in there to cry for 30 (2 15 min increments) minutes and I had to go get her she sounded miserable!!

What happened to my sleep trained baby!

Please help!!!

Any advice?

Sincerely,

Sleep deprived