What are some ways you can regulate your circadian rhythm naturally and without the use of light or darkness?

Setting rhythm: The most important cues to setting your circadian rhythm are light, food, and physical activity. Getting good sleep is important. If you are a shift worker and your light/dark is reversed, it is important to focus on good sleep hygiene and then eat at predictable times and get exercise, best after awakening.

Zeitgeber: you should try and look up zeitgebers. They are what help to entrain us to our 24 hour circadian rhythm. Light is the strongest of zeitgebers, however there are some medications that may help. keeping a regular bedtime/wake time and meal times may also help.