HTC One Power Saver


I’ve recently converted from the iPhone 5 to the HTC One and absolutely love it, I can’t believe it took me so long. Anyway, I've read in quite a few posts/forums that turning on Power Saver mode increases the battery time by a significant amount but obviously turns off the data when the screen is off.

My question is this: is there an exemption for push notifications from apps like Whatsapp, Twitter, Facebook etc.? I use Whatsapp as my main form of messaging and wouldn't want a delay in messages being received.

Please help an Android newbie? Thanks!