: being, having, characterized by, or occurring in approximately 24-hour periods or cycles (as of biological activity or function)
The word CIRCADIAN is often followed by the word rhythms, suggesting a habitual repetition or pattern happening during regular 24-hour periods. So, for example, if I set aside an isolated chunk of 24 hours to combing the beach with a metal detector, it would not be CIRCADIAN, it would be absurd. However, if I combed the beach with a metal detector every day at 3 pm for a half hour one could refer to this activity as CIRCADIAN. And still, of course, absurd.
CIRCADIAN derives from the words "circa" (about) and "dies" (day). Circa is really a wonderful word. It allows its user to be vague while also still sounding intelligent and professional. Circa says: I don't really know the answer, it's probably around this time, about this figure, sort of like this—I'm not really sure.
Circa: making uncertainty sound trustworthy for two millennia.
An art history professor of mine consistently took points off exams if you neglected to include the "circa" next to an artwork's date. It seemed excessive at the time, but the circa is important. It suggests an estimate, an inability to pinpoint something, the effort exerted in trying to locate the means, and finally, a defeat.
Okay, so, sleeping in the darkness and waking with the light are biological CIRCADIAN activities. I'm sure the word can also apply to learned or cultural activities, such as: breakfast, rush hour traffic, prime-time television, etc.
Caffeine: totally CIRCADIAN.
This is a great word for the habitual, the obsessive-compulsive, the routine-loving individual. Every day is a pattern, a series of repetitive and comforting activities. Would utter CIRCADIA be the state of perfectly executed routines? A land where everything is always operating as usual—you never wake up to an empty carton of milk or a creak in your neck or a houseguest. Comfortably dull. While I adore my routines, a break from the CIRCADIAN is often welcomed, if not just absolutely needed. I sometimes have to remind myself not only that there are options but also that I should take advantage of them.
The CIRCADIAN is the reliable structure from which to break away. The sun will always rise and set. Take comfort in this home base, tether yourself to day and night, and then let go.