The sleep lab

I know this post is a little later than usual. Unless I have something that I'm super jazzed to talk about, I normally write on my Saturday mornings. Occasionally I will have calls/meeting on Saturday mornings (which are actually Friday afternoon meetings in Canada) that disrupt my regular routine. If I'm writing a lot at work, and my normal writing time is gone, I find it much harder to get things out. Today I've decided to go a bit outside my comfort zone and do some blogging while at work so I can talk about some cool stuff from last week.

Overall the day to day in Australia is starting to feel much more routine. And while obviously there will be more passionfruit-esque experiences in the future, I'm kind of enjoying getting back to the mundane regularity of working a 9 to 5. That said, there are lots of fun things happening at work. Yes, there is still lots of reading. But I also got to do some super cool training in the sleep lab last week.

The sleep lab is both exactly as it sounds (a lab where people sleep) and so much more than you would expect (tons of equipment and tools for monitoring & sampling of participants). The sleep lab is where sleep studies take place (duh): people come to the lab in the evenings, get hooked up to machines, sleep, and then go home in the morning. The sleep lab participant part includes 4 bedrooms, each with their own bathroom and computer, while the hallway outside is full of computers, monitors and equipment. There is also a kitchen, a small bio lab (for biological samples - blood, urine, saliva), offices and lounge areas for both the participants and researchers.

In the sleep lab, they monitor sleep (again, duh). But what does that actually mean? We all know that sometimes you wake up and feel great, and other times you wake up and feel like crap. Sometimes there is an attributable cause (going to bed late, alcohol, stress, etc), but other times it feels very random. Turns out, there are things we can do to measure how 'good' your sleep is.

Aside: Please keep in mind that we are now tiptoeing into the world of science, which means 'good' doesn't necessarily mean the 'good' you would use in everyday conversation. Rather it means a very narrow definition that the science has decided is optimal. Basically, someone can have a 'good' night sleep according to science because their body & brain behaved a certain way. But that doesn't mean that the person would wake up in the morning & describe their sleep as 'good'. Yay for scientific pedantry!

So how do you measure sleep? The same way you measure so many other body things - with electrodes! Anytime there is a medical test or procedure called an electro-something-o-gram (or electro-something-ography) it means we are using electrodes (usually on the skin) to measure the electrical activity of an internal structure. By far the most common example of this is an electrocardiogram (ECG), where electrodes on the chest are used to measure heart activity. This same basic principle is used in electroencephalography (EEG), where electrodes on the scalp are used to measure brain activity (for all my standardized test takers out there - encephalo is to brain as cardio is to heart).

Of course, there are a couple of challenges associated with EEGs over ECGs. You figure out where to put the electrodes by landmarking based on structures you can see/feel on the outside of the body. Conveniently, the heart is located in a literal bone cage (aka rib cage) with numbered bars (aka ribs). If you have ever felt someone press strangely on your chest when putting on ECG electrodes, its because they are landmarking & counting your ribs. Unfortunately, skulls do not have a lot of landmarks (note that we are talking about the cranium part of the skull - yes, its actual name - not the face part of the skull). And while skulls aren't usually covered with clothing, they do have the issue of hair to deal with. Both of these factors (+ some physiology ones related to the brain that I'm not going to get into) make EEGs more challenging to set up (imho) than ECGs.

First lets talk about landmarks. Because there are so few, and they are all essentially on the edges, someone devised a system of ratios and measurements to approximate how to find where the parts of the brain are on the skull. So the first step of EEG is to literally start measuring the participants head. Like with a measuring tape. Specifically you are looking for the measurement from your nasal bridge (between your eyebrows, aka the nasion) to the boney ridge at the back of your skull (the very top of your neck, where your skull ends and your neck starts, aka the anion); and the measurement over the top of your head, from right in front of one earhole to another. Based on these two measurements, and where these imaginary lines cross, you can essentially create a 'grid' over the top of the skull. Yes, there are clearly challenges related to trying to imposed a 2D grid onto a 3D structure. I'm not getting into that because it is a lot.

Lets move onto our next problem - hair. We overcome this one with wax. Specifically, a special conductive electrode wax. While ECG electrodes have a conductive material surrounded by a sticker, EEG electrodes are attached via conductive paste + secondary, even stickier wax (if your hair is longer than ~3") + a small square of gauze. You part the hair to expose the skin where the electrode needs to go, prep & clean the skin, then sort of smush the electrode on. Then its more wax, some gauze, and you fold the hair back over. I can't tell if it sounds simple or not, but it definitely isn't easy to master the first time you try it. As you can imagine, its very easy to lose track of where the electrode is supposed to go, or get it stuck in hair rather than attached the skin.

To get a better understanding of someone's sleep, you need more than just brain activity. So on top of the ~10 EEG electrodes on the skull, participants also get electrodes on the chin (to measure jaw clenching), around the eyes (to monitor eye movements), a speaker at the throat (to measure snoring). ECG electrodes on the chest (to measure heart activity), a positional monitor (to detect your body position), leg electrodes (to measure leg movement), and a thermistor and nasal canula to measure both nose and mouth breathing. Its a lot. I legitimately don't know how people sleep with everything hooked up.

The training for the sleep lab, was very much a 'learn by doing' activity. Of course, they weren't going to let us touch actual research participants, so we got to practice on each other. The set up is significant enough that the learning portion was broken up into parts. Then the last activity of the day was learning how to calibrate and troubleshoot all of the monitors. For that, someone had to be fully hooked up. Of course you all know I volunteered. To be fair, I didn't just volunteer because I am a huge dork that thinks these kinds of things are cool. The group that was training was mostly very awkward undergraduate honours students that really weren't used to the idea of someone else touching them. After years of paramedic training & work, I'm essentially immune to any embarrassment that comes with having a relative stranger attach things to your body.

So, dear readers, I present to you: The top part of the sleep lab set up!