The company that I mainly work with is owned by a guy with STRANGE sleep habits.
He often wakes up at midnight or 1:00 AM, drives to the office to do paperwork, then to the job. We used to start at the half hour closest to sunrise but over the past couple of years, we had jobs away from residents so we were able to start at 6:00 or 6:30 regardless of the time of year. Because of that, we all started wearing those hardhat mounted bright halogen lights to see. Sometimes it was dark for about an hour before the sun was up.
The owner leaves the job at quitting time, eats at home then goes to sleep and the cycle begins again. He is tired and sleepy by quitting time so the earlier we start, the sooner he can get home to sleep. If the guys would be willing to start at 4:00 AM or earlier, he would probably LOVE it!
Try operating forklifts, power saws, walking scaffold, taking measurements when it is PITCH black!