(Pocket-lint) - Switching on dark mode on your iPhone actually can save battery life. 

That's the finding of a test from PhoneBuff who deployed an identical iPhone XS firstly in light mode and then in dark mode and then ran several tests to mimic identical everyday uses of the device.

The battery life was compared as time went on, with the phone set to 200 nits of brightness in each instance.  

The most striking thing about the test is how easy it was to see the difference - just using the Messages app for two hours (between chatbots, in case you were wondering) the difference was 5 percent of battery.

Scrolling through Twitter, again for two hours, saw an even bigger difference, with 26 percent of battery lost on the light mode iPhone and just 16 percent on the dark mode device. So four hours use saved 14 percent of battery life. 

There was a 23 percent difference just six hours in, which is an incredible difference in such a short period of time. The caveat is that only apps were used which have a dark mode, many still don't. 

Remember that the XS is an OLED device - like the iPhone X and iPhone 11 Pro. The iPhone XR and 11 don't have OLED displays. Dark mode is more effective in terms of power frugality on OLED devices. 

Here's the video of the full test. 

Writing by Dan Grabham.