Moto X Battery Life

I've recently been on a quest to improve the battery life on my Moto X. When I started, my phone would typically last about 12 hours on a charge, even when I was hardly using it throughout the day. With some luck and experimentation I found that Moves and Google Keep both eat away at my battery throughout the day. Moves is an app that records all of your movements, and its battery usage makes sense. But I have no idea why Keep keeps waking up. Perhaps to sync reminders? Who knows. For now, both are disabled and when my phone is idle my battery settings percentage bar chart looks like this:


I wonder why Android OS uses such a large percentage of my battery. Time to dig deeper.