So, Oathbringer has quite a few references to the Sleepless. The one that has stood out the most to me has to be from page 438, during Dalinar's vision of Aharietiam, we get:
Now, this has multiple implications.
1. Tighter Aimian - Human relations than what we see in modern day. The Aimian actively opposed Odium's encroaching forces.
2. Something has occurred since Aharietiam that has caused the Sleepless to avoid open communication with humanity. Likely related to the disaster said to have scoured Aimia of most of it's people.
Thoughts?