No I don't. But I did and yep the biological clock was really screwed up by working a shift that ran around the clock. You find yourself sleeping odd hours, out of sync with the 24 hour rhythm that your body is designed with. Sooner or later something will "break" and that will be your health. Your immune system will decline over a period of time, your ability to reason and think and both short term and long term memory recall will be messed up. Being "tired" all the time is either you are sleepy or you are physically fatigued. Sleepy is one thing, physical fatigue is a whole other ballpark. Do it long enough and you will become a perpetual insomniac who will require either drugs to sleep (and drugs to wake up). If you work the grave yard shift, your best bet is to live the grave yard shift even on weekends - this will keep your body and your mind from trying to break out of a diurnal period, even if it is nocturnal. If you are the type of person where just one hour of daylight savings really messes up your internal clock, then you need to seriously get a job where you work the same hours. No two people are the same, some can (and do) thrive on these work schedules where they sleep at different times, then there are people who must be in bed by 9:05 PM and wake up at 5:10 Am or their whole day if not the following week is shot. If not changing jobs is in your cards, then I strongly urge you to see a doctor soonest to talk to him/her about your alternatives to light therapy to offset some of the issues of sleeping weird shifts. Bright light when you wake to "set" the clock for the day has been shown to help millions to over come things like jet lag, insomnia, etc.

I used to have to work horrible shifts..and I read somewhere years ago that shift work, on average, shortens your life span by up to 12 years. I was chronically tired--so was everyone I worked with.

I'm retired but I go to bed about 4 am & wake up about 1 pm

I work changeable shifts and I actually like it. I can adjust pretty easily. And it seems to make the work week go smoother. And I can have daytime often for running around and taking care of business during the day when necessary.