What Are Circadian Rhythms

All of us experience a change in sleeping patterns at some point of time or the other. Most nurses who do the ‘graveyard shift’ will find that their body takes some time to adjust to a new ‘sleeping pattern’ when they’re bumped back to the afternoon or morning shift.

Why does this happen?
Thanks to the study of chronobiology, which dates back as far as the 4th century BC, observations related to this biological process known as circadian rhythms have been made. Yet it was Jurgen Aschoff, who co-founded the field of chronobiology, who is credited with the discovery of circadian rhythms – the name which is used to describe the aforementioned biological process.

But what are circadian rhythms?

The word ‘circadian’ is derived from the Latin term “circa diem”, which when translated to English means ‘about a day’. According to the good doctor, and consequent discoveries in this field, it is observed that plants, animals and humans follow certain physical, mental and behavioral patterns (rhythms) that oscillate every 24 hours due to the presence of a circadian clock. Scientists say that these circadian rhythms are mostly developed due to the day-night cycle that repeats over 24 hours.

An interesting example is what causes you to wake up in the morning – yes, sunlight is the reason why we’re awake. Conversely, the clock usually suggests that we should go to bed as it gets late at night.

What this should also tell you is that the organism in question, is ‘entrained’ by certain “cues” in its environment (in this case, the day-night cycle) to exhibit certain behaviors – and this is why you’ll find that people feel sleepy at night, and will wake up anywhere between 5 to 9 AM every day.

However, it’s not just light that works as a zeitgeber (‘time giver’ in German) but there are other cues that affect circadian rhythms. Temperature, sounds, pharmacological manipulation and so on and so forth are other cues that play a part in maintaining clock-environment synchrony.

Simply put, external stimuli (zeitgebers) influence changes to these internal rhythms and which reset the circadian clock after a period of 24 hours is complete.

So how is this study of ‘circadian rhythms’ useful?

There are a host of sleeping disorders, insomnia for one, that affects our health including the link between circadian rhythms and depression, bipolar disorder and seasonal affective disorder.

In understanding how these rhythms work, it might provide researchers with clues as to how these diseases can be treated.

For the rest of us, understanding circadian rhythms only further our understanding about how complex and intricate the human body truly is.

A Great Video – How does our circadian rhythm influence our sleep

Thanks for watching!