Originally Posted by Whyzor
Download & run the CPU Spy app from market. Reset the counter, then turn off screen, wait 5-10 seconds. turn it on and refresh, you should see the deep sleep mode register (among other frequencies from the interactive part). If deep sleep doesn't appear, it takes some investigation into what apps you have installed and the settings in them that keeps them awake. Start with settings - applications - running services.
The only ones that I have running are settings, juicedefender, google services, maps and android keyboard. It won't go into deep sleep. I closed settings then opened cpu spy.