Circadian (10): Midday

If you think what you have read so far about what your body does in response to night and morning is life-changing, brace yourself for something even more monumental. A lot of people, both in the conventional and alternative worlds, talk about circadian rhythm but they end up making the same mistake. They stop at what happens at night and make this their primary focus, when night is really only the beginning.

There is no bigger lever to pull for our circadian biology than the peak of midday. This is where everything circadian culminates. It is the more significant half of the clock puzzle, such that the whole body is wired in synchronisation with this energy-laden moment. Think about it: before we came along, 99.99% of our kind lived in a binary environment of dark and light. The hormones we talked about and the genes we will touch on are hard-wired to the natural light environment, such that our departure from this state will always come with a cost—big or little—whether we register it or not. It doesn’t mean, however, that we can’t stay up for a few nights a month to get some really important things done; it just means that the body will need to recalibrate itself to fix the compromised equilibrium.

I differ greatly from the psychologist Michael Breus, whose idea of chronotypes has been received well by many internet wellness warriors. This leads to people claiming that they have a chronotype that does not necessarily follow the sun; essentially, a lot of them use this as an excuse to fuel their habit of working on their computers late at night. It is no wonder that they won’t wake up until late morning and have low productivity until late afternoon or early evening. This is the sort of selection bias trapped in its own feedback loop. You know, the ‘rut’ I was talking about in the last article.

Ironically, three years before Dr. Breus made his ideas public, a professor in behavioral neuroscience, Kenneth Wright, conducted an experiment which proved Michael wrong long before his book was published. He took people from the late-night chronotype camping out in the bush with zero artificial light for a week—within which time everyone’s clock synchronised perfectly with the sun. He took their salivary melatonin samples every 30 to 60 minutes before and after the experiment and was able to see that at the end of the study, the participants were all producing melatonin beginning at sunset. This is proof that the proponents of Dr. Breus’ idea wrongly treated phenotype (how genes express themselves in different environments) as genotype (an unchangeable blueprint).

I am talking about this because I have met people who turn up at my clinic claiming to have the "wolf" (late night) chronotype, when I could see every twist and break in the physiology that screams out the opposite. They will stay up late, wake up late, and—most importantly—they will consistently miss the midday sun exposure, and the cycle repeats. You should now be able to at least understand that they will have issues with maintaining serenity (serotonin), healing injuries (NREM III), and sorting out emotional trauma (REM). What you are yet to learn is how they are also prone to getting chronic diseases of all kinds—and why. One day, if I am able to articulate this well, you might even understand why some people get one kind of disease and others get another.

Let’s start our lesson with the genes, as I have alluded. Do you remember the building with its windows all covered in Circadian 1? Well, in the 1970s, we thought that the manager was all we needed for the rest of the building to tell time. This manager lives in the brain; a structure we call the suprachiasmatic nucleus (SCN). We identified the genes that govern time in the SCN and called them CLOCK, BMAL1, PER, and CRY.

Just before the turn of the century, we realised that this assumption was folly. Scientists experimented with mice organs and figured out that their clocks ticked independently from the SCN while they were on separate petri dishes. Soon after, human tissue biopsies were demonstrated to do the same petri-dish performance. Every department of the building—or human body—has an independent clock, and each of them needs to "see" time. The manager, or SCN, did not enforce time on the different departments; it simply reaffirmed what is already there. If the SCN finds that the whole body is working on the same clock, it is able to ensure peak performance. On the contrary, if it finds that the body is out of sync, performance stalls.

So these CLOCK, BMAL1, PER, and CRY genes are in every cell of our body. The first two, CLOCK and BMAL1 proteins, are activated at dawn as our natural light environment changes. But at this time, most of our skin is blocked from registering the dawn light—we are hidden behind four walls, with blackout curtains, under thick blankets, and in pyjamas. Instead, the cells learn to make these proteins at the right time because of a consistent pattern of midday exposure that penetrates through to every cell. When the cells understand midday, they can accurately determine midnight and dawn. With this understanding, a little bit of help from the minor brightness (5-10 lux) that hits your eyelid is enough to trigger a whole cascade of processes for the body to wake up, with CLOCK and BMAL1 proteins in the lead.

What do they do? Well, everything that I told you the body does at dawn—cortisol, TSH, testosterone, noradrenaline, dopamine, DHEAS, etc. The body ‘knows’ what to make and when because of CLOCK and BMAL1’s appearance in each cell. These gene transcription factors make nearly everything that we need to function in the day, including PER and CRY, which actually go against them and block their function. The longer CLOCK and BMAL1 have been working, the more PER and CRY there will be around. The more PER and CRY there are around, the weaker CLOCK and BMAL1 get, until they are fully restrained in mid-evening. PER and CRY take over for all of our nighttime functions like melatonin, PTH, prolactin, occludin, and growth hormone. Fortunately, PER and CRY degrade after a few hours to allow CLOCK and BMAL1 to work again at about dawn. The whole cycle generally takes about 24 hours to complete. In essence, the movement of the earth and the sun leaves an indelible imprint in our genes. Now, is it a coincidence, or should we call it intelligent design?