So Miles fell asleep last "night" at 4:30 PM. I thought I was taking a nap with him, but he just never woke up. He woke up around 10:30 when we were brushing our teeth, because we were too loud (and he was sleeping in our bed). We put him in his crib, and they slept until around 4:30 AM. We fed them, and then they slept until 8 AM. So Miles slept 15.5 hours last night alone, not to mention the naps he took today.
I think he might be having a growth spurt or something.