Default Light themed or dark themed?

Hello friends,
Can you tell me, what kind of themed z1c themes are better for battery saving?
Light or dark?

Thanks and regards, Chris

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My active devices:
Sony Xperia Tablet Z SPG321 LTE - AOKP-KitKat-Nightly ROM
Sony Xperia Z1 Compact - Munjenis Custom Stock Rom - rooted