I had this problem with my xperia Z ultra. Something to do with the 3G network which causes battery drain. Uninstalled it on that, didn't see a difference.
I use fast reboot to clear ram on my phone, and it pops up with com.sonyerricson.android.wakeup which is in fact fast dormancy.
I'm now using 4G and I guess its still running! Causing battery drain. But as I'm not rooted I can't check wakelock detector to see If it is actually draining battery.
So annoyed by this, my galaxy s3 didn't have this problem
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