That's only somewhat true. If you're exposed to sunlight during the day, much brighter than a lit room, it will tend to have an influence on your circadian rhy

That's only somewhat true. If you're exposed to sunlight during the day, much brighter than a lit room, it will tend to have an influence on your circadian rhythm. You might be able to sleep at arbitrary offsets but the quality of your sleep will suffer. Though wearing sunglasses when outside during the morning will help you get to sleep later and wearing them outside during the afternoon will help you sleep earlier. And I'm not aware of research showing a problem with shifting your sleep to arbitrary offsets if you're never exposed to sunlight, though that might have other bad effects.