Diurnal rhythms are biological processes that occur in a 24-hour cycle. The environment can influence these cycles, such as light and temperature. They may or may not have anything to do with circadian rhythms.
Some examples of diurnal in daily life include the release of microfilariae from Loa loa into the peripheral blood, which occurs predominantly during daylight hours, and plasma cortisol levels, which increase throughout the day.
Your body has an internal clock in the form of your brain called a suprachiasmatic nucleus (SCN). It's located next to where you keep all those important neurological networks, like vision and hearing. The SCN regulates sleep patterns or hunger hormones throughout each day with signals sent out through cool mathematical equations.
Each type of biological rhythm has a certain name to show how long it lasts:
Unlike circadian rhythms, which are primarily environmental and determined by the day you eat or sleep at night, diurnal processes such as body temperature vary throughout a 24-hour cycle. This means that they change every 12 hours like most other things on Earth, i.e., although some people's temperatures may rise more than usual around noon.
On the other hand, circadian rhythms are a natural phenomenon that helps determine when you should be asleep and wake up. Your body's internal clock adjusts to local environmental cues, such as light or temperature changes, someone living on Earth has their optimal sleeping/waking cycle.
In humans, this adjustment happens through something called "zeitgebers,” the word zeitgeber derives from a combination of two German terms, Zeit, which means "time," and Geber, which means "giver”. So, a zeitgeber is a "time giver" that includes things like how bright it is outside vs. what time of year we're having.
To learn more about Diurnal and Circadian rythms, visit our blog section.