Circadian Rhythm

The circadian rhythm is like a biological clock that is built into each and every individual. It is what controls three of your major biological processes: sleeping, eating, and mating. Circadian comes from the latin words "circa" and "diem" which translates to "about a day," which is actually quite fitting since the circadian rhythm is in fact how your body keeps in time with day and night.

So, how does this all work? Your circadian rhythm is sinked to the rising and setting of the sun. It is run by the hypothalamus, or more specifically, a bundle of nerves in the hypothalamus known as the Suprachiasmatic  Nucleus (SCN). The SCN is attached to your optic nerve which is why it responds so well to changes in light. When light appears, hormones are released, which in turn, causes your body begin ramping up its biological processes. Body temperature increases, heart rate increases, blood pressure increases, bowel movements are no longer suppressed (because they are during the night which is why you don't wake up covered in crap) and there is a delay to hormones that aid with sleep, such as melatonin. In relation to this, studies have also shown that through the morning there is an increase to memory, alertness and concentration which results with us being at our cognitive best in the late morning. After that there is a cognitive decline in the early afternoon followed by a second spike in activity. You see, while the urge to sleep is greatest from 2am-4am, the second strongest desire to sleep is actually between 2pm-3pm. What this means (and it is good news for anyone who likes an afternoon nap) is that napping may be an important part of our day. There are a few theories as to why, such as it may have been better for our distant ancestors to rest during the hottest part of the day, but no one really knows for sure exactly why this is.

Where we get into trouble is when we start messing with our internal clocks. As you are probably well aware, our daily routines no longer coincide with sunrise and sunset. The advent of artificial light means we can work, play, and do whatever we want, well into the night (or as early as you want if you are crazy). This can be especially dangerous to shift workers, who should attempt to maintain their internal clock as regulated as possible since disruptions in our natural circadian rhythms have been linked to health issues including: diabetes, obesity, depression, dementia and mood disorders. In other-words, listen to your body as it generally knows what's best when it comes to being asleep and being awake.