I just stumbled across the answer to this in a Kiefer interview by Sean Hyson. http://www.seanhyson.com/blog/carb-backloading-qs-kiefer-as-part-iSean: One question I see all the time is if [Carb Back-loading] can be done even when your body clock is totally out of whack with the time of day. You say cortisol peaks at 7 a.m., but what if you work nights and go to bed at around 5 a.m.? Would cortisol then rise toward the end of your sleep cycle, even though it’s later in the day—around 1 p.m., maybe—or is it hardwired to rise at 7 a.m.Kiefer: Some people will sleep in a room without blacking out all the sunlight. In those instances, the body stays pretty close to regular circadian rhythms. Your body will still try to be in tune with sunlight if you’re not blocking out sun. But then you have people who are up all night and then basically make a cave for themselves when they sleep, and there’s not as much research on that. It does shift, but it’s somewhat erratic. I’ve worked with people where it’s appeared to have shifted perfectly with their sleep cycle. So even though they’re waking up at 6 p.m., everything is normal. And then I’ve worked with people where it just didn’t seem to benefit them… I would recommend still doing back-loading as advertised. I would avoid food when you first get up. People in those instances who are the most successful also train right after they get up. So maybe they’re getting up at 7 p.m., training, and then going off to work at night.Sean: So then that guy’s 7 p.m. is like our 7 a.m.?Kiefer: Correct. In a way, it makes it nice for those people. They get to enjoy the breakfast foods. [When they get back from work, it’s most people’s breakfast time, and since they’ve already trained] they can have pancakes, [hash browns, other starchy or sugary carbs].