If we didn’t add an extra second to the clock, sometime a few million years from now, humans or their descendants will sleep till noon. But for now, it’s a real stress on may business who worry their websites may crash — and Google’s trying to block it.
Leap seconds don't come on a regular schedule because Earth's rotation varies, says Demetrios Matsakis, chief scientist for time services with the United States Naval Observatory in Washington D.C. Our planet is slowing down, but it does so in unpredictable ways. So some periods require more leap seconds than others. http://news.nationalgeographic.com/2015/06/150629-leap-second-atomic-astronomical-time-earth-rotation-physics/