The human circadian rhythm is a universally accepted framework for the body having it's own internal clock that determines optimal times to sleep, eat, move, think, work, etc. You can see this in Nature with her own rhythms: day and night, the lunar cycle, and the seasons (like animals hibernating). And our rhythm can change over the years. So a toddler's cycle will look different from a teenager and from a middle-aged adult. Unsurprisingly, Traditional Chinese Medicine, Indian Ayurveda, and other traditional medicine systems factor in the circadian rhythm when treating ailments and providing solutions. For example, skin cells are known to turn over every 28 days, so it can take a minimum of one month to notice improvements or changes.
Many factors can affect one's circadian rhythm, yet the biggest impact comes from light and dark. Therefore the quality of light can make a big difference. One of the top recommendations is to go outside and look at natural daylight first thing in the morning to help "set" your body's rhythm for the day. Looking at the light through glass or lenses blocks the benefit, so open the window or step outside, and remember to remove your glasses or contacts if you use them. We know morning light timing can change during the year depending on the season, but the concept of getting outside first thing when it's light is important. Also, turn on and up the lights inside during the day! Obviously if you need to watch your energy bill then it's up to you how much, but the more light exposure during daylight hours, the better for the body's sytems.
The opposite goes for when the sun has set and it gets dark, whever you live. Ideally, we want to turn down the lights inside when it's dark, or even use candles. Incandescent light bulbs have more natural light spectrum available than LEDs, so if possible, turn off the fluroscent and LED lights in your home. Also critical within two hours of bed time is minimizing or eliminating the use of screens, which emit blue light - a known sleep disruptor. Other things that affect your rhythm includes food, activity, stress, travel (jetlag!), medications, and even sleep (or lack thereof).
Becoming aware of and learning to live within your circadian rhythm can start from a general "template" that works for most people your age and sex. The key is to observe your own patterns and tweak your lifestyle as needed to fit with your natural energy flow. Then establish a daily/nightly routine that you generally hold to (regardless of the day of the week) to help your body realign with it's natural circadian rhythm.