All spoilers, all the time!
I am just finishing my second read through of both Way of Kings and Words of Radiance and it's occurring to me that Kaladin almost certainly has a chemical imbalance of some sort, most likely bipolar disorder. There are actually several different types of bipolar and he'd most likely suffer from a rapid cycling version, which would keep him out of long periods of dark dangerous depressions.
Couldn't even guess if he was written from the start with the idea that he behaves as a person with the disorder would or if it's just coincidental.
I cherry picked put some of the major symptoms as they apply to him from specific interactions and actions in the book.
Depressive/dysthymic episodes. Symptoms of the depressive/dysthymic phase include difficulty making decisions, guilt, self-criticism, low self-esteem, pessimism, self-destructive thinking, apathy, hopelessness, helplessness and irritability. Also common are quick temper, poor judgment, lack of motivation, social withdrawal, self-neglect, fatigue.[9]
Hypomanic episodes. Symptoms of the hypomanic episode include unusually good mood or cheerfulness (euphoria), extreme optimism, inflated self-esteem, rapid speech, racing thoughts, aggressive or hostile behavior, lack of consideration for others, agitation, massively increased physical activity, risky behavior, spending sprees, increased drive to perform or achieve goals, decreased need for sleep.
Thinking about his flip flop from being ready to drop himself into a chasm, to driving himself beyond the limits of human endurance to get the bridge crew to follow him.
Also his near constant moodiness in WoR is another big indicator.
Thought it would be fun to discuss in any event.