💤 Cracking the Enigma of Sleep
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💤 Cracking the Enigma of Sleep
Have you ever suffered from a lack of sleep? Have you ever wondered why we sleep in the first place? Join us to learn about the neurology of sleep and how you can control it.
An introduction to neurological cryptography
(just an edgy subtitle, it’s not complicated, don’t worry)
It’s a dreary afternoon when a telegraph operator in Bletchley Park sends out the following signal:
— — . — — —
An office in King’s Cross receives it. A rather plump man wearing a black suit and smoking a pipe begrudgingly taps out the same signal:
— — . — — —
An operator in a somewhat grander building in Whitechapel receives the message and send’s her own:
… — — — — . — — .
Finally, this is received by Battersea power station, which reduces the supply of coal going into its furnace and the amount of energy produced.
(If you don’t know morse code the first two messages spell out ‘go’ and the last ‘stop’.)
Believe it or not our brains operate in a very similar fashion to the telegram operators that we met in just a moment ago. After all, our brains are essentially a network of interconnected neurons (the offices) that send out electrical impulses (the morse code). Indeed the signals transmitted in the brains are even simpler morse code, either there is a signal or there isn’t. A 0 or a 1. To complicate matters slightly some neurons are excitatory, whilst other’s are inhibitors.
Let’s first look at the excitatory neuron. When it receives a signal, it will emit excitatory chemicals to activate a nearby neuron. This is like the operator at Bletchley sending a ‘go’ signal to King’s Cross. However, there are also inhibitory neurons. These may recieve an excitatory ‘go’ input but they will release inhibitory ‘stop’ chemicals to nearby neurons. This is like the operator at Whitechapel sending a ‘stop’ morse code even though she received a ‘go’. One final thing to mention is that neurons integrate signals. So in reality the operator at Whitechapel would likely recieve signals from several areas (perhaps Fulham, Highgate, Islington, Camden and Mayfair), then only if there are enough stimulatory signals converge on Whitechapel will the operator send a ‘stop’ signal to the power station. So although the impulse of a neuron is all-or-nothing, the activation of a neuron leading to an impulse is graded.
Ok, where am I going with this you might wonder? …
Well understanding the above paragraph is pretty much all you need to understand the neural mechanisms behind sleep and pretty much an other neural pathway. So let’s just dive right into a bit or neuroscience and specifically the brain circuits that put us to sleep. Because, if we understand these, we will understand how to manipulate them. This will help improve the quality of our sleep and ultimately live happier, healthier, lives.
The Brain Circuits of Sleep
The primary inhibitory chemical in the brain, and the one most closely associated with sleep, is called GABA (gamma-amino-butyric acid). This is why many sedative drugs such as benzodiazepines target GABA receptors. But that’s a story for another time. The neurons that release this chemical, in the context of sleep, are found in the ventrolateral (bottom) and median (central) pre-optic areas (basically the centre of the brain). This is one of the oldest parts of the brain and often regulates unconscious activities. This suggests that sleep evolved a long time ago and also that we can’t consciously decided to fall asleep at any given moment, which I feel is a lost opportunity on the part of evolution.
In any case, the neurons in this area are most active in non-REM sleep (when you just go to bed) and least active during wakefulness. The exact pathway of the these neurons rests on a ‘switch’. This is the ‘wake-sleep’ switch, which receives inhibitory inputs from the pro-optic area and excitatory inputs from elsewhere. It is the balance between these inputs that determines the state of the brain: awake, asleep or somewhere in between. Consequently, this ‘switch’ is very much like Whitechapel in our story. A central hub, where impulses converge the balancing of which, either switches off or switches on the ‘Battersea power station’ of the brain.
Indeed, once the inhibitory signals converging on the ventrolateral preoptic area fall below a certain threshold then a wave of inhibitory impulses are sent out inhibiting the ventrolateral periaqueductal grey, the pontine tegmentum, the monoamine system, which sound like cult names but are actually regions of the brain associated with wakefulness.
Ok, we’re done with the jargon, you can take a breath now.
In essence, there is a switch in the brain which is suppressed by the excitatory regions of the brain. When these excitations begin to diminish (when we’re tires) this switch is flipped and a huge burst of GABA floods the brain inhibiting activity, which leads to sleep.
Why Do We Sleep?
This is a question that people have asked for … well as long as there have been people and although we may not know everything yet, we do have a few good ideas. One of the current hypotheses is called homeostatic plasticity. The idea is that as we use our brains a build up of toxic chemical occurs known as somnogens. These are a direct by product of neuronal processing i.e thinking. When we sleep these somnogens are cleared away restoring our ability to process the vital information of a cat meme on the following day. From this perspective, sleep is the price we pay for having a brain, which on balance seems like quite a good deal. Perhaps evolution didn’t mess up after all. Consequently, sleep is vital to our health and a new trend is emerging, which sees sleep as a preventative measure to stave off neurological decline. As we have already seen in a previous publication, matcha may be another way so be sure to check out that article.
“Toward this end, an emphasis on looking at sleep health as a preventive measure in the effort to stave off neurologic decline is growing in evidence-based support and clinical awareness.”
So now we know how sleep works, we know what it’s for and why it’s important so what can we do about it?
Modulating our Sleep
(aka: The rise of the floofy blankets)
A meta-analysis (analysis of an analysis and yes the paper is as dry as it sounds) published in 2021, investigated the potential benefits of several supplements on sleep quality. The reason why a meta-analysis is so useful is that the exact same study conducted twice can give different results due to the nature of probability. Doing a meta-analysis helps us to be more sure (although not completely) in our conclusions. If you want to read more on this take a look at ‘beware the man of one study’. Another thing to be aware of is that the meta-analysis can only express a relative improvement. This is because different studies look at different parameters (e.g duration, quality, or sleep latency). Consequently, this study decided to look at the difference in the means as a measure of improvement. In this article I will state the values for you to be able to compare the supplements but just be aware that this is not an absolute measure of efficacy.
Keeping the statistical limitations in mind, the paper found some interesting results.
The supplement that brought about the greatest benefit according to the analysis was Vitamin-D. The data for this is based on five studies conducted between 2017, and 2018. The study reports a mean difference -1.63 with a 95% confidence interval of (-3.15, -0.10). This means that the true value has a 95% chance of being inside that range.
The analysis also looked across seven trials of melatonin supplements and found a mean difference of -1.21 with a CI (95% confidence interval) of (-2.17, -0.24).
The last supplement to have a significant impact was amino acid supplements with a mean difference of -1.27 and a CI of (-2.35, -0.20)
Conclusions
Does this mean we should all feverishly run to the nearest store and intravenously administer vitamin-D directly into our veins as if the end of times is upon us? Probably not. Indeed, some of us are lucky enough to be able to get a solid 8 hours of sleep each night, for whom it is unlikely that supplements are necessary. However, there are those who struggle to sleep adequately, either they work night shifts, look after children, or have a sleeping condition. For those, it may be worthwhile to think about ways of improving their sleep. This may include a supplement, alternatively it may include improving the environment in which they sleep (e.g the correct temperature and light levels), which unfortunately we will not have chance to explore in this article. However, even in those cases always make sure to follow the respective guidelines on the packaging and, as always, the advice of your health professional.
Yegor Lisle (he/him) is a UCL MSci Pharmacology student. He is curious about the nature of biology, the origin of life, and the biochemistry of the universe. In particular he wants to understand more about the interface between biology, chemistry and physics.