Love Sleeping In? Turns Out it’s Genetic

By Calvin J.

If you’re anything like me, you love sleeping in. I purposefully invested in a set of noise-reducing curtains just so I could snooze till on my weekends. There really is no comfort like that of letting yourself drift right back into sweet-slumber after waking up a little “too early” on a Saturday morning. But one of the regrettable side effect is that agonizing return to a 6AM wakeup call the following Monday. I know I’m not the only one who tortures themselves with this weekly cycle of self-induced jet lag. So then why do we do this? Is it true? Are night owls like me just lazy or is it in our biology?

rats2.pngIn a way, our bodies function like a clock –

– rhythmically in tune with the natural day-night cycle of our planet. Our “circadian rhythm” defines our daily activities. We tend to be our most energetic during the peak of the day, and slow down as the evening rolls in. It’s a direct reflection of the hunter/gatherer days of our early ancestors. We would come out to hunt and feed under the safety of broad daylight, and halt our activities when the night came in. After all, we’re not built to see in the dark.

Our circadian rhythm is largely regulated in our brains, by the superchiasmatic nucleus or SCN. It’s a pretty intimidating name for a small pocket of about 20,000 neurons, but together, they signal the day-night cycle to the rest of our body. They regulate the cyclic secretion of cortisol during the day, and melatonin during night.

But how then does the SCN know what time of the day it is? Well, part of it is genetic, regulated by so-called “clock genes“. They’re DNA feedback loops that come full circle approximately every 24 hours, turning on and off to signal the start and end of a day-night cycle. But to really keep it in sync with our natural environment, we need to thank the sun. Exposure to bright lights stimulate its activity. Which is they say you shouldn’t be staring at a computer screen right before you go to bed (whoops…), the bright light coming in through our eyes fool our SCN into thinking that the sun is still up. Meaning that while you might consciously think its your bed time, your body thinks it’s the middle of the day.

But while choosing to binge watch Netflix till 4 in the morning might be a personal lifestyle choice, the concept of early risers and night owls is actually strongly rooted in science. While our SCN does its best to be relatively in sync with the natural day-night cycle of our planet – meaning you’re typically awake by 1pm when the sun is at its highest – it doesn’t necessarily mean that it’s identical from person to person.

rat.pngOur sleep-wake cycles are called chronotypes –

and we each have our own. While 30-50% of people fall within the average chronotype – sleeping between the hours of 11pm and 7pm – there are a lot of us who don’t fall neatly into this category. Just like how height varies from person to person, chronotypes range between early and late sleepers. This means that while most of us might call it “sleeping in”, biologically speaking, we just have a later chronotype. In fact, chronotypes can get pretty extreme. Those with Delayed Sleep Phase Disorders can have circadian rhythms, drastically different from the social norm. For instance, some people may naturally sleep between 3PM to 11AM.

So it’s not really my fault that my body is naturally built to sleep a little bit later than the average person. But while it’s literally beyond my control, it doesn’t mean there aren’t consequences. Our society runs alongside the average human chronotype, and for people whose biological clocks are a little out of sync, this can mean a whole lot more than missing a couple of hours of sleep every Monday morning. As we shift out of our body’s natural circadian rhythm to match our society’s schedule we are putting ourselves in a chronic cycle of self-induced sleep deprivation.

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A phenomenon aptly termed “social jet lag” –

it’s not only a nuisance but it also has huge health ramifications. In a Harvard Medical study, when healthy participant’s sleep schedules were purposefully disrupted periodically – similar to how your circadian rhythm may be disrupted as you transitioned from a day off to a work day – the researchers found a drastic decrease in the participant’s metabolic rates and their pancreatic beta cell counts. Both of which are early signs of obesity and diabetes. When you aren’t getting enough sleep you’re more likely to over-eat, due to a misregulation of your hunger hormones. Likewise, insufficient sleep is also associated with increased chances of heart disease, higher blood pressure and can cause damage to your arteries. Science has also shown that experiencing “social jet lag” can have a number of psychological effects as well, including depression, poor academic performance and an increased likelihood to engage in risky behaviours like smoking.

Horrified yet? I know I am. But the thing is, our biological clocks are so engrained into our bodies that there isn’t really any way around it. While our SCN functions as the master clock for our bodies, every single one of our cells are busy counting its own time. Every cell expresses the same clock genes, and they in turn help regulate the activity of up 20% of the cell’s other genes.

asdf.pngSo what’s a night owl to do in a world of early risers?

Well, in truth, there isn’t much we can do. Our society favours those with average chronotypes, and I just wasn’t lucky enough to inherit one. Living with “social jet lag” is about a lot more than missing a couple hours of sleep here and there. It’s a chronic phenomenon with detrimental effects on our physical and mental health. I for one wish that our society would recognize that. It’s time to set aside silly stereotypes about early birds catching the worm. Early risers aren’t more virtuous (maybe just luckier) and there’s no shame in being a night owl. Why can’t we all just live to the rhythm of our own circadian clocks?

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