Sleep wake disorders breathing related sleep disorders | Behavior | MCAT | Khan Academy


– [Instructor] When we think
about breathing problems at night we can think about the problem coming from three key areas. The first one being a problem
arising from the brain and the brain being a key
central organ that controls the respiratory centers that
help regulate the lungs. So, the brain is really important here. And the second one being a
problem with upper airways. So if there is any
obstruction to the airways from the mouth and the noise to the lungs that can cause a problem. And last but not least, we can also have a problem with the lungs themselves or the chest wall. Anything that stops the lungs
from being able to expand out. So, let us take each one of
these things as step by step. And let us start by
looking at the airways. So, the main issue with the
airways is that obstruction to the airways causes
a significant problem in terms of breathing at night. And if we consider the air
that goes in through our nose and in through our
mouth reaches our lungs, we have points at which the
soft tissues around our neck may potentially relax at night and they may potentially block
this airflow intermittently. They may potentially cause an
obstruction to this airflow. And when they cause an
obstruction to this airflow you may notice some snoring or gasping. And this suggests that the
airflow is being stopped. That term is, for a lack of airflow, it’s called an apnea. And all that apnea really means is that there is an absence of airflow. So, if the airways are obstructed we can have something called Obstructive Sleep Apnea. And this condition, Obstructive Sleep Apnea, is actually very common. It gets worse as people get older. These soft tissues block
this airflow that we have and this condition actually
results in a variety of daytime and night-time symptoms. So, we actually mentioned some of the night-time symptoms, right? We mentioned this kind of
snoring, gasping for air, and these kind of apneas, these kind of pauses, breaks in the breathing where
there’s a lack of airflow. This condition also poses
problems during the daytime because during the daytime people can feel very tired and sleepy. And they may particularly comment that their sleep is never refreshing, so they wake up feeling unrefreshed. So, that’s a little bit about
this Obstructive Sleep Apnea. And the way that we diagnose it, we do a sleep study or a polysomnography. And what we’re looking for is 15 or more of these apneas that not only have pauses in the breathing but you can also demonstrate
evidence of the person’s having obstruction in
the airways per hour. And that’s done on the sleep study, on the polysomnography. So, that’s a little bit about
Obstructive Sleep Apnea. That’s a very important cause of Breathing Related Sleep Disorders. Alrighty. So, we’ve got obstructed sleep apnea but what happens if there’s
something that is wrong with the actual brain? Now, the brain is part of the
central nervous system, right? So this is actually termed
something different. This is termed Central Sleep Apnea. So, the way that we can thing about it, again, we have this apnea, which is this lack of… Complete stop in airflow. We have sleep cause it’s
going to happen at night, the breathing’s going
to be effected at night, and we have central because the brain is part of the central nervous system, and that’s where there’s a malfunction of the centers that
help control breathing. And what we’re looking for here is the presence of these apneas but there is no obstruction. Again, on the polysomnography we’re only looking for five or more. These are kind of the arbitrary
criteria that are used. We’re looking for five or
more of these apneas per hour to be happening during sleep. And really when we think about the apneas we believe that the Central Sleep Apnea, that there’s a problem with
the brain’s control system for ventilation. So basically, the parts of the brain that help control the breathing, they are malfunctioning. Now, I’m just going to talk
to you about a particular type of breathing malfunction that happens in the Central Sleep Apnea. And I’m just going to
spend a second on that. If we consider our normal
breathing to be in and out; inhale, exhale, inhale,
exhale on this graph there’s a particular type of
breathing that we see sometimes in Central Sleep Apnea and
it looks something like this. It’s a crescendo-decrescendo
apnea type displace. So, let me show you. So, we have the crescendo decrescendo then we have an apnea. No breathing. And then again it starts. Crescendo, decrescendo, apnea. And it carries on like that. And this is actually
something that’s called Cheyne-Stokes Breathing. And with this Cheyne-Stokes
Breathing we believe that this is particularly
related to Central Sleep Apnea that’s as a result of heart failure, strokes, and renal disease. Renal failure, I should say. Okay. So, we talked a little
bit about the brain being a site of malfunctioning and we talked a little bit
about the airways being a site of obstruction. Now, finally the lungs. The lungs need to inflate and deflate when we breath in and out. So, any process that stops
the lungs from inflating or deflating appropriately is
going to cause us a problem. So, when we think about the
lungs we can actually have something called
Hypoventilation Disorders. Disorders of sleep
associated hypoventilation. And when we say hypoventilation normally when we breath in and out we get rid of carbon dioxide but unfortunately when we don’t breath in and out enough, when we don’t ventilate our lungs enough, we can get a build up of carbon dioxide. And in some cases we can
also not have enough oxygen. Now, these kind of
hypoventilation problems with our breathing can occur
because there’s a problem with the lungs, the chest wall, if we’re using some medications that depress our respiratory function. Like narcotic painkillers for example. If somebody is very obese and just the sheer amount of
obesity reduces their ability to breath in and out and
ventilate their lungs. And the problem here is that
this chronically elevated carbon dioxide poses a problem
because it can actually result in right sided heart failure. And never mind our low oxygen because one of the things that we know is that our brain, our heart, pretty much all the organs in our body need oxygen to function. So, if we have a low oxygen we’re going to have problems
with our brain over time, especially chronically, we could have a degree
of cognitive impairment. We may have problems with our heart. Some people may develop arrhythmias, abnormal heart rhythms. Again, over time. And also our blood as well. So, we can develop polycythemia
which is a very elevated amount of red blood cells in our blood. And this can also be a problem. That can cause it’s own
huge range of complications. So, as we can see here, Breathing Related Sleep Disorders, we can really break them down into these three big categories. Are they related to the airways? Obstructive Sleep Apnea. Are they related to the brain? Central Sleep Apnea. Or are they related to the chest wall, the lungs, this kind of sleep
associated hypoventilation conditions or disorders?

6 thoughts on “Sleep wake disorders breathing related sleep disorders | Behavior | MCAT | Khan Academy

  1. Another masterpiece in description, however as a Psychology student I was hoping more a more psychological center around sleep/wake disorders (like the description you gave on the brain, but looking for a more variance on causes for this disorder) and hoping to see a more variety of disorders (if there is any). Thanks and great job!

  2. Not sure if this is a sleep disorder or not but I fall asleep fine, same time every night. During the night I never sleep solidly, I wake up a lot. I don't actually get up but I do move around in bed. Conscious enough to know I'm alert.

  3. Given that insomnia I got was not truly serious, so I did not take it significantly. Not until Five years later where it is now the worst issue. I can just sleep at night just for 3 hours in almost all nights and I cannot also sleep through the night on most occasions. I applied “Fαnvοkα Fawam” (Google it). I experienced the positive effect exactly on the day I started utilizing it. In only one week I was asleep 4-7 hrs every night. And it also carries on to enhance a lot better as I continually apply the guide. .

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