Polysomnography: A word long enough to put you to sleep!

So, how did you sleep?

I ask with a greater level of intrigue than simply for the commitment of connecting with you. I ask, because I care. I ask because I am a scientist.

A hundred or so years ago, what we knew about sleep was that we sleep to alleviate sleepiness. Considering that humans spend nearly a third of our lives in the sleeping state, it should come as no surprise that I (and many sleep researchers before me) remain unsatisfied with that deduction. The velocity of sleep research had been exponentiated by Hans Berger’s measurements of the brain’s electrical activity, depicted as waveforms, which he called an electroencephalogram.

Since the tool of electroencephalography (or, EEG) came to the slumber party in the 1920’s, sleep scientists began inquiring into the effects of sleep deprivation on the body, the role of sleep on cognitive power and, remarkably, observing that different stages of sleep occur in cycles through the night. All this is possible with the understanding of the brain as a battery – a component in a circuit that has a finite capacity for work with the inevitable outcome of needing a recharge.

When you are in a state of wakeful awareness, following demands of “to-do” lists and preparing for meetings, your brain may be functioning at maximum capacity. Daydreaming on a walk through a park during lunchtime requires the brain to be far less acutely involved in paying attention. As you read, meditate, or begin drifting off to dreamland, the output of your brain slows down sequentially and allows the initiation of sleep.

A person’s sleep and wakefulness is partially at the mercy of the usual “sleep-hygiene” factors:

  • timing and amount of caffeine intake
  • the stimulation of light exposure and humidity of the sleep environment
  • stressful events in one’s day
  • the body’s apparent chronobiology
  • what was eaten before bed…

The phenomenon of sleep is as unique to your body and lifestyle as the print on your fingertips!

Yet, there are numerous internal decision-makers for adequate or disturbed sleep – some of which the sleeper may not even be aware of.

I work as a collaborator with a team of remarkable clinicians at Ezintsha, a research centre located adjacent to Wits Health Sciences campus, for patients with illnesses like TB or HIV that drive major public health issues in South Africa. The HIV epidemic is currently rather well managed by the early-stage intervention and widespread distribution of antiretroviral therapies across South Africa. This follows nearly three decades of devastation. However, with the prolonged life expectancy and improved quality of life available to people living with HIV, epidemiologists observed the inflation of other devastating epidemics like hypertension, diabetes, metabolic syndrome, and heart attacks.

Cardiometabolic risk indicators like high blood pressure, sugar intolerance and cholesterol imbalances are on the rise, and researchers in HIV-related trials begin to engage with a new class of reported symptoms: those of obstructive sleep apnoea. Obstructive sleep apnoea describes the short-lived but repeated pauses in breathing during sleep, often indicated by snoring. This is frightening to both the patient and housemates who have heard the gasping snores that accompany the breathless event but fear not! Obstructive sleep apnoea is treatable.

So, why is this story important?

Sleep apnoea remains underdiagnosed in the general South African population, despite as many as 30% of people being at risk for this sleep-related breathing disorder. Its side effects include daytime sleepiness, chronic inflammation, reduced motivation, brain fog, changes in mood and of course a further rise in those nasty cardiometabolic risk factors. Cardiometabolic diseases are responsible for one out of every five deaths in South Africa. This is a public health crisis, which we can aim to mitigate with routine diagnostics for obstructive sleep apnoea.

Without the foundation of an EEG, an even more comprehensive sleep measurement tool would never have been possible. Cue, polysomnography! Polysomnography measures brainwaves in various sleep stages, but the addition of other physiological measurements like heart rate, chest and belly movement, blood oxygen levels and air moving through the nose opens the door to diagnosing obstructive sleep apnoea through overnight sleep observation – which is exactly what I do! Polysomnography tells the story of how we sleep – I am simply the reader.