Android M’s Doze mode has been attracting much attention due to the battery optimization it supposedly provides. During the testing phase, the Doze mode apparently reduced the power consumption of the device by drastic amounts increasing the standby time by twice.
The Doze mode puts apps into a low-power state that keeps them from consuming much power. However, there may be apps that you may want to keep out of the Doze mode’s influence — Your alarm clock for example, which may fail to ring in Doze mode.
Not to worry, Google has made allowances for that in the latest Android M. To remove an app from the aura of influence of the Doze mode, simply go to device settings> Advanced > Ignore optimizations and voila! The app will work even in Doze mode.
Of course it’s too early to say anything for certain and if the feature will even be present in the actual Android M that releases in the fall. However, judging by the fact that Google Play Services, the Play Store, and Download Manager are set to ignore optimization procedures by default, that may just be a possibility.