Ruby Pryde - Jan 11 2021

The science of sleep: the sleep-wake cycle

Sleep can be one of the more challenging areas of health we face in the modern era. The likes of late night television, our phones and computers at our fingertips, and forever operating nightlife, basically at our doorsteps.

So it’s really no wonder the temptation to stay awake for ‘just another hour' is so easy to give into.

Whilst sleep is arguably one of the most important factors that contribute to better health, it unfortunately is one of the most overlooked.

We’ve taken a deep dive into all things snoozing - focusing not only on the importance of sleep, but actually taking a proper look into what our sleep cycle is, how it works and what the effects of a mistreated one can be.

Rather than just telling you to get to bed on time (nothing new there), we thought we’d try to offer a better understanding of why it’s so important.

Our sleep-wake cycle - what is it?

Our sleep-wake cycle, by definition, refers to our 24 hour daily sleep pattern which consists of approximately 16 hours of daytime wakefulness and 8 hours of night time sleep.

Now before we continue, we wanted to make note of two very important players in the operating of this cycle.

Cortisol: a steroid hormone that assists the body in responding to stress. Stimulates wakefulness in the morning as well as supporting alertness throughout the day.

Melatonin: a hormone produced by the pineal gland that assists the body in responding to darkness and inducing sleep.

Right, so now we have those covered, let’s get into it...

The body’s internal body clock is located in the hypothalamus and is controlled by an area called the suprachiasmatic nucleus (SCN), which is sensitive to the signals of light and dark.

Running by the course of a natural sleep wake cycle, (ahem, you mean in a perfect world?) our hormones, specifically cortisol and melatonin, are in tune with the cycle of the sun. Ideally this would mean that cortisol is higher in the morning and then kept steady throughout the day, to then drop as the day winds down, in turn allowing melatonin to rise in preparation for sleep.

The key to remember here is that if we aren’t adhering to this natural cycle externally, our body is going to be unable to maintain it internally.

Our ancestors, in conjunction with their sleep wake cycles, used the sun in order to prepare for their days and nights. They would naturally wake up with the rising of the sun, work hard alongside the big dose of morning cortisol, and then begin to wind down for the evening as the sun began to set and their melatonin levels began to rise. The only light used at night would be fire. And whilst we are by no means living in those times anymore, our bodies are still attuned to this cycle. We’ve just built our lives around it.

Now just because we have built our lives around this cycle, it doesn’t necessarily mean we’ve been respecting it. Our circadian cycles, especially when we’re busy, has become nothing more than just a biological clock that we have a not so great tendency to adjust and manipulate according to our schedules. But does it actually work?

Sadly, no. Humans are somewhat convinced that we have the ability to outsmart just about anything (thank you ego), but our bodies are unfortunately not one of them. They may adapt for a short period of time, but eventually our bodies will begin to give us signals that it’s had enough. Think: regular headaches, a sore back, brain fog and a weakened immune system. Yep, that’s your bod telling you it’s time to slow things down! 

So what does our sleep-wake cycle look like to our body? 

If we’re asleep, beginning around 10:00pm, is when our bodies will begin to undertake physical repair. Things like muscle repair, inflammation reduction, removing of waste, cell repair, energy restoration and even the reorganisation of nerves occur during this time.

Lasting up until about 2:00am, our brain then turns over to the psychological repair, lasting until 6:00am or so, or when we rise. Things such as restoring your mental exertion, decreasing depression and the processing of different types of psychological information occurs here.

Now if we’re going to bed later than 10:00pm, as much as we’d like to think it is - our body isn’t waiting ever so patiently for us to hop under the covers and turn the lights off. If you miss for example, the first two hours of the physical repair window and hop into bed at midnight, then that’s it.

You don’t get those two hours back. Your body simply carries on from the time in which you fell asleep. As a result, rather than its expected four hours of physical repair, it’s only getting at best two. So in saying this, we don’t mean hopping into bed at 10:00pm and reading for an hour. We mean BE asleep by 10:00pm.

Particularly if you are someone who needs an hour or two to wind down, this is even more crucial to understand as you will need to factor in this time to your evening routine.

It may be an adjustment to what you’re currently used to, but try it for a week and you’ll be amazed at the results both in and out of your slumber.

And so, with a better understanding of how our body actually operates during the night, check back in next week for a look at what disrupts our sleep cycle and why!

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How to Eat, Move and Be Healthy - Paul Chek