The Stamina Mode was introduced by Sony on its smartphones long back. This mode, when activated, stops unauthorized apps from running in the background or running sync jobs. Thus, it helps preserve battery life. The company had removed Stamina Mode earlier, but now, the company is planning to bring it back to Xperia Beta Program soon.

According to Xperia Blog reports, Stamina Mode is back for real on NTT Docomo's Xperia Z4, Xperia Z5, Xperia Z5 Compact and Z5 Premium devices. From the Japanese carrier, these have received an OTA update to Marshmallow. Soon it is going to be available across the world on other Marshmallow builds. No firm schedule is given though. Earlier, Sony had taken the Stamina Mode out of the early Marshmallow builds due to its interference with Android 6.0 Doze Mode.

Somehow, Sony has found a way to make Stamina and Doze co-exist. A lot of Sony fans prefer Stamina Mode as it works all the time (and not just when the phones are stationary) and has user-facing options. There are additional options like reduced performance, stamina clock and the ability to whitelist apps. It also includes the Ultra Stamina mode, which converts the Smartphones to feature phones.

This allows users to make only calls and send texts. But it is not sure if Stamina Mode will operate the same way in Marshmallow. Meanwhile, Google's Doze is only activated whenever the phone is stationary for some time. However, Google said that it does not want any interference of OEMs with the way Doze mode operates.

From the last few months, the Xperia Beta Program has been running and is expected to last for a few more months. It is currently made available only to the recent Z series devices and is also limited to a few European countries.