Tuesday, January 7, 2014

The Neuroscience of Slumber

Unlike the lass above (or fraulein, as that's a German painting), I couldn't sleep the other night. This is not an uncommon occurrence for me and for millions of us who spend nights staring at the ceiling, tossing and turning and making sleep difficult for their significant others. I normally do pretty well with it, to be honest. My health condition is closely linked to sleep and as sleep is very important to manage this condition, I learned to master sleep. But even at that, now and again it's a problem for me. For many people, however, it's a chronic problem.  Since I needed a new column for this blog and since I couldn't sleep, I thought I'd knock off two birds with one stone and read up on the neuroscience of sleep and produce something useful whilst my mind refused to be seduced into slumber. 

Our sleep is at least somewhat governed by our circadian rhythm. Now what is that and how does that get governed? A circadian rhythm is:
 any biological process that displays endogenous, entrainable oscillations of about 24 hours. These rhythms are driven by a "circadian clock" and rhythms have been widely observed in plants, animals, fungi and cyanobacteria. The term "ciradian" comes form the Latin "circa", meaning "around" or "approximately" and "diem" meaning "day". (1)

Now where would this circadian "clock" be? Do we have a piece of little Swiss handy work in us somewhere? Well, no. As we should know by now, just as Apple "has an app for that", the brain has an "app" - a specific brain region - for all of our functions so let's have a look at what brain regions are involved in sleep (and this will be an incomplete list, but we're just looking at the basics today). 

This is why most of us get jet lag when we travel to far away time zones - our ciradian clocks get all thrown off. 

The little brain nodule that rules our sleep rhythms appears to be in the suprachiasmatic nucleus region of the hypothalamus. The hypothalamus - not to be confused with the thalamus - is in our limbic region which lies below our outer cortex. We should be by now getting familiar with the limbic region (and if not, back to neuroscience 101 with you). So inability to sleep could mean the SCN region of the hypothalamus is too stimulated or, more likely, not receiving enough "it's dark out" messages from some special neurons in the retina. These neurons have specifically evolved to detect and be activated by certain wavelengths of light that come at the end of the daylight period just before it turns dark. They then send this message onto the hypothalamus. Let's have a look. 

The hypothalamus is responsible for some pretty basic stuff, as you'll see in this illustration. So you can see that a lot of basic "drives" we have are located here and - back to our topic - so it is with basic sleep cycles. I'll sometimes refer to the brain functions being "bottom up" in nature, that is what drives your thoughts is driven from these "bottom" regions and not the other way around. 

The sub-region that regulates the circidian rhythm, the suprachiasmatic nucleus is, obviously, located where it says "sleep-wake".

Now you see how clever the brain design is? (I say "design" but of course I mean how cleverly it evolved). It routes the optic nerve, in that part called the optic chiasm, so that those "it's dark now" signals from the special neurons in the retina can be dropped off in the SCN so that it can start sending other signals out to other parts of the brain that it's time to shut down. So part of our modern problems with sleep is that we no longer "listen" to these signals. We evolved to follow the rhythm of natural light cycles but today we ignore these and "override" them thus possibly disrupting how our circidian rhythms work. 

So that region is one factor in our wake/sleep cycles and their disruptions. 

Now, another culprit for sleeplesness could be an even deeper brain nodule, the locus ceoruleus. This fellow's sole purpose in life is to crank norepinephrine throughout your brain. Norepinephrine is a major "wakefulness" neurotransmitter. If you can't seem to "wake up", then it could well be your locus ceoruleus is not working up to snuff (for possible reasons far too deep for us here today). And no, coffee - or caffeine - doesn't go down there (though caffeine will sorta mimic norepinephrine). Conversely, if you're lying wide awake at 3am feeling "wired" (and without any stimulants), it could be that your LC is hyperactive for some reason.

Here's the locus ceoruleus and its pathways. 

Overabundence of neropinephrine is a suspected factor in the manic phases of bipolar disorder (which is my particular condition so this bad boy has probably been working overtime - literally - in me recently). What's not well known is how the two regions we've looked at here - the hypothalamus and the locus ceruleus - work together or not but it appears as though the hypothalamus is in the "norepinephrine loop" meaning that the SCN could be receiving this stimulant thus having its "clock rhythm" thrown out.  

So we possibly have two very deep subconscious brain structures in rebellion and not allowing you to sleep. 

There's more though - anxiety is no doubt also playing a role. When anxiety strikes, almost your whole limbic system is on high alert, mostly, perhaps, the cingulate gyrus (which is thought to produce that dread feeling of anxiety) and this is often where that "racing mind" feeling comes from. Again, this is a "bottom up" pathway - from the limbic region to your "seat of thoughts" - so again, we have another deep brain region driving you. And as the cingulate gyrus is part of our elementary "threat alert" system (or stress response system) its role is to force "what could be wrong" thoughts into you conscious awareness which could then be keeping you awake (which is kind of their point - they're designed to make you do something about the ideas it's presenting of "what's wrong"). Anxiety - what's really low level chronic stress - is going to make it really difficult to relax and go to sleep which is why people often turn to anti-anxiety drugs or even anti-psychotics - they can inhibit circuitry activity to and from this region and thus "knock down" those anxious thoughts. But this is a poor long term strategy (for various drug side affect and long term drug addiction problems). It might be better to start working on the basis for those feelings of anxiety (which may or not be imagined). 

Now, what happens when your brain runs down from too little sleep? Well, I could flood you with the science on this and, trust me, none of it is good. Brains absolutely need to sleep no matter how "tough" you think you are about not needing sleep. As the old TV ad used to go, "you can pay me now, or you can pay me later". In other words, you will pay later in life for depriving your brain of sleep. 

And you'll pay in the short term too, the brain just does not function as well on too little sleep. Even in peak conditions the brain does not fire up every region at one time. It "prioritizes"; it only sends energy to those parts of the brain that it thinks are necessary at any given time. And if your brain starts getting tired, it will - with absolutely zero input from "you" - start shutting further regions down to prioritize and conserve energy usage. And guess what your brain considers "non-vital" operations? Your cortical regions, especially your "seat of control", the frontal cortex. Your basic survival instincts and functions are in the limbic region and brain stem so the brain will send more energy there. Which means, hey, more energy to your emotional regions! And you wonder why you get cranky and more emotional when you get tired. As well, your brain will dial back energy to your frontal cortex, which is where your functions of concentration, focus, judgement and higher thinking are, the very things you need to get through that afternoon meeting with the boss. You'll be staring bleary eyed at your boss really regretting staying up half the night on Facebook, I tell ya. 

That's the short term downside to lack of sleep. I know for many of you lack of sleep is a chronic problem. 

Let's have a wake up call on this (pardon the pun) and look at the long term. Remember glia cells from Neuroscience 101? I said we'd be looking more at these little guys and now is the time. 

The science on glia cells and their exact roles is not completely understood and established (and as you can see, there are different types of glia cells doing different things) but the roles of glia cells appear to be so many and so critical that I could easily fill a whole column. Here though is the best basic way to look at them; they are very critical support systems for neurons, dendrite growth (remember, it's dendrites that form key inter-neuron communication connections ... more in a moment) and axon maintenance and two of the more critical roles are supplying neurons with oxygen and other nutrients and - here's the big take away for today - it appears more and more that glia cells are critical for flushing out toxins. And the grand poompah tie in to today's lesson? It's even more and more appearing that glia cells need - ta-da!! - sleep to do their job. Yes, they're the night crew that comes in and cleans up after the day crew. 

Just briefly, it goes like this. Neurons take in nutrients. Neurons are cells. All cells produce waste. Neurons thus produce waste. You know, nutrients in, waste out. All living things are like this. Waste doesn't just disappear into thin air. Someone has to deal with it. And it appears that when it comes to the neurons in your brain that glia cells are that "someone". So to put it another way, neurons produce poop and glia cells are the pooper-scoopers. And the glia cells need you to "shut down things" - IE: sleep - for them to do their job properly. Plus - PLUS! - if you don't shut things down, then the neurons will still be "up" and - ta-da! - still producing neuron poop. So not only are you not allowing the night shift glia cells time to do their job, you're piling up more neuron poop in your brain! Now do you really want to go around the next day with a head full of neuron poop? Ever wonder why you're so groggy when you don't sleep? Well, yeah, it could be a lack of norepinephrine but it could also mean that, because the night crew couldn't do their jobs, you've got a head full of neuron poop. Or what the more scholarly articles call "toxins". Yes, toxins - waste products of brain functions - will build up from chronic lack of sleep. Very, very not good, people. 


Now back to dendrites and glia cells. Dendrites are the little spikes on neurons that receive signals from other cells. They are, therefore, utterly critical to all brain functions - IE: the passing of information from one neuron to another and thus "thought". Back to Neuroscience 101, dendrites also grow and prune back all the time. When not needed - a memory falls into disuse and the information from a particular neuron is no longer needed, for example - dendrites prune back. But what we need to sear into our memories today is the growing part. Dendrite growth is what makes the learning of new information possible. Learning stimulates dendrite growth. It's critical for new learning to "stick" in our memories for dendrites to seek out new connections with neighbouring neurons and pathways and then to strengthen those new connections. It's these new connections that make learning - and remembering - the new information possible. Quite simply, if those dendrites don't do their thing then learning is not going to happen. And back to glia cells, what helps dendrites grow and seek new connections and then strengthen them? Glia cells it appears. And what is essential for glia cells to do their thing? Once again, sleep. This is why sleep and proper rest have always been considered so important for learning; it's because that without it the dendrite growth essential for new connections - and thus learning and remembering - is simply not going to happen. Meditative breaks during the day help as well but that's for another day. 

Sleep is also essential for reducing stress and the less sleep we get, the more stress will build up and stress as well greatly negatively impacts brain performance thus creating a cycle of poorer daytime performance building more stress (and worry and anxiety) which further impacts sleep and rest and so on. So learning to get a better night's sleep is crucial in helping to break that cycle. You get better sleep, you perform better in the daytime, you perform better in the daytime you stress less and get to sleep easier and on and on. 

"OK", you're saying, "this is all good and fine, Brad, but what the hell do we do about it??". 

I thought you'd never ask. I mentioned the "bottom up" nature of brain functions. Here's where we're going to learn some "top down" management techniques to get those rebel brain regions at least somewhat under control. 

First up is the very thing right before you now as you read this post. The light from the screens of all our various electronic devices is not good for those special neurons in the retinas of the eyes we talked about that are responsible for sensing oncoming darkness. The light wave that emits from device screens - be it TVs, computer screens, tablet screens or handheld devices - is the same wavelength of light in the DAWN sky. So yeah, if you use a device late in the evening before bed? You're sending wavelengths of light that are telling your circadian cycle it's time to get up! Which makes it pretty hard for your eyeballs to communicate to your suprachiasmatic nucleus in your hypothalamus to tell it to kick the circadian rhythm into gear. So it is the light from screens of devices that is almost certainly playing a big part your difficulty in sleeping. Not to mention that what you're reading is probably getting your limbic region all in a huff (and anxious).  

So what to do? This is where you need to make an "executive - IE: top down - decision" and set a limit and stick to it. No more electronic devices after a certain hour and then make that a habit. Need help with that habit? I can think of nothing better than to go to behavioural change expert, Stanford professor Kelly McGonigal whose book The Willpower Instinct is just by far the best I've seen for learning and implementing new habits. And she not only has great habit change techniques, but also good meditation techniques. Win/win there, baby. 

I know - I know - how hard it is to turn your brain off in the evening. You're a busy person, I know. But here's the thing - you'd get a LOT more done during the day with a well rested and maintained brain and thus not feel so anxious in the evening about undone things! Yes, yes, easier said than done; I know. But hey, everything worthwhile takes effort. So give yourself lots of time to wind down. If your sleep time target is 10pm, stop device use by 9.

Then - and this is important - make a list of things to do the next day. This will send a message to your brain that says, "yo, cingulate gyrus (remember, that anxiety centre I told you about), we got this stuff covered. Going to do it all tomorrow just like the list says. So you can relax and go to sleep." And then DO that stuff that next day or the next time you write your list your brain will think you're lying (brains are awfully smart about these things). This is just a terrific habit to get into before bed time. 

You could do a little light reading to feel sleepy. I know books are almost guaranteed to put me asleep in the late evening. You just don't want anything too demanding. Remember, you're trying to dial your brain activity back, not ramp it up. 

Next, you're going to meditate. Turn off all lights and just ... well, I don't have time for a meditation lesson here now but I use an extremely simple one of counting as I breathe in and then out and focusing on those breathes. Inhale - one-two-three, exhale - one-two-three. The key thing is to focus on your breathes. It takes practice, I can tell you, but after several weeks, you'll start to get it. Once I mastered this (after only a few weeks), I'd do my counting and measured breathing techniques for not too long and the next thing I knew it was the next morning and I'd slept like a log.

So not being on a device, making the list for the next day, and doing the sleep time meditating is going to calm some of those deep regions in your brain down. As for longer term ways to deal with stress, I can think of no better methods than my very own Positive Difference Making Fundamentals. I've got a LOT of feedback on these from people "in the know", shall I say. They work.

OK, you say, you can fall asleep but wake up at 2am and can't get back to sleep. I totally hear you on that one. Happens to me often too. The thing to do here is not get into a habit of doing things once you're awake. I won't turn on the light or do anything. I'll keep my eyes closed and repeat my meditative techniques. And if that doesn't get me back to sleep, I'll still be keeping my brain in the most restive state possible. Or it may take an hour but I'll still manage to fall asleep for another few hours of valuable sleep.  

And this is the last big take away for today. Any habit - ANY habit - takes time to change so go easy on yourself if it doesn't go well at first. Most people freak out, throw up their hands and give up if it doesn't happen the first night. This is a journey. It takes time. The goal is to be getting to sleep earlier and getting better sleep in - say - a month or so. Just stick to the fundamentals I gave you here - and maybe research some more on your own - and you'll get there. I promise.

And just think - that next big board meeting? (or whatever it is you do that's important) You'll not be showing up all groggy from a brain full of neuron poop. 

You're welcome. 


(1) - Wikipedia

Kelly McGonigal's The Willpower Instinct

Many scholarly articles like this onethis one and this one.

More studies on the importance of sleep in forming new memories

David Suzuki's The Nature of Things

Plus, you can find more ways to beat insomnia here.

Good night and sleep tight. 

PS - sorry about the font size issues. It looks formatted properly in the composition box but then when posted some font sizes where bold or within a link come out larger. 

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