For me the problem is that I can't sync to the light day without really forcing myself — and I can only force myself so much. A day according to my biological c

For me the problem is that I can't sync to the light day without really forcing myself — and I can only force myself so much. A day according to my biological clock is slightly longer that 24 hours, so with nothing to keep me in sync since I graduated from the university, my sleeping schedule is always slowly drifting. At some point it gets inverted and then goes back to normal. Without me disciplining myself at all (not forcing to go to bed at X time and not using an alarm), one cycle of this takes approximately 2 weeks.