A couple of my friends I know that used to work at IHOP, always wanted to work graveyard shifts and they were happy about it. However, it had a toll on their sleep and stress psychologically. As a result, they were not doing this job because they had to, but because they wanted to make money. On the contrary, I remember my mom had to work graveyard shifts because she had to work for a living. Both experiences help me understand the relationship between work and intelligence because there is both work ethic and there is knowledge about the work you do.