Galaxy S5 :: Why Does Screen Turns On Every 15 Seconds While Phone Is Charging

My S5's screen turns on every 15 seconds or so while the phone is charging. Its not that big a deal, but I can't imagine it causes the phone to charge faster when it is turning on the screen all the time.

What's odd is that it stops doing it when my phone gets to 90%-charged. From 90% to 100%, it doesn't do it, but any percentage lower than 90%, it turns on about every 15-20 seconds and stays on for like 2 seconds, turns itself off, then turns on again 15 seconds later.I have browsed through the Settings pages, but can't find anything that looks like a way to stop this.