Overview of biological circadian clock in humans. Biological clock affects the daily rhythm of many physiological processes. This diagram depicts the circadian patterns typical of someone who rises early in morning, eats lunch around noon, and sleeps at night (10 p.m.). Although circadian rhythms tend to be synchronized with cycles of light and dark, other factors - such as ambient temperature, meal times, stress and exercise - can influence the timing as well.HH: I think my clock has always been a bit off. I can become nocturnal pretty quickly, however I love the early mornings. I just like a siesta in the afternoon whenever possible and then I am going late into the night/early mornings.I have to constantly fight this because I work a day job. But when I retire, I am going to be religious about “organic” waking and sleeping - when I feel like it.