Obstructive Sleep Apnea

  1. Do you snore?
  2. Do you persistently feel tired and sleepy in the daytime?

If you’ve answered yes to these questions then there is a good chance that you’re experiencing a form of sleep disorder called sleep apnea.

Whenever I mention this term to the patients, they almost always seem to have heard of it but almost equally tend to have very little understanding of what it means.

The reason more people are hearing about it is because the rates of it are going up. Statistics show that about 25% of Australian men and about 9% women tend to have clinically significant OSA. Out of these, about 4% will have symptomatically significant OSA. It is relevant and important as it leads to an increase in death rate by about 2.5 folds. People with OSA are 7 times more likely to develop heart disease, weight gain, have decreased levels of concentration and mental sharpness or alertness and up to 9 times more likely to have motor vehicle accidents.

So let’s talk and learn a bit more about it. Apnea comes from Ancient Greek word: a = absence, pnein = to breathe.

So the basic pathology in OSA is a blockage in the upper respiratory tract during sleep that leads to recurrent stops or pauses in breathing.

Now lets explore this blockage business a little bit further. During sleep the air enters through our nostrils and passes via the throat, down into the lungs. Our clever bodies have evolved in a way that allows the muscles at the back of the throat to relax a bit as we are breathing in, to allow this air transition to occur without us having any awareness of it. So if all is going well then you’ll either hear no sound coming from the person sleeping next to you or it may be a gentle and quiet rhythmic sound of deep breathing.

But in individuals with problems in the area, these muscles may relax a bit too much, gradually narrowing the passageway of the air and you may hear the person lying next to you breathe quite noisily and start snoring and the intensity of the snores may keep going up in a crescendo rhythm (partners have described it as the sound of a train approaching the station – gradually getting louder and louder). The over-relaxed muscles at the back of the throat eventually collapse down, completely clogging up the path of the air getting into the lungs and the breathing stops – at this stage you suddenly hear….nothing. This is where the apnea or absence of breathing happens. Then the reflexes of the body kick in, causing the person to gasp for air, which you may hear as a gurgle or startled breathing sound coming from them which then again settles into a gradually increasing intensity of snores and the whole cycle carries on throughout the night.

Quite often the person who is going through it will have almost no recollection or recognition of these events as it is happening in the unconscious state of sleep, albeit the quality of sleep is affected, unbeknownst to the sufferer. It is not unusual for the spouses to come to doctors with the problem with a disgruntled partner who can’t see what the fuss is all about!

So, the above explains what it is and how it manifests but it still doesn’t explain how it can make the sufferer feel so tired and sleepy in the daytime that it has become almost the hallmark of sleep apnea presentation. The tiredness can be explained with the changes in sleep cycle.

During a normal sleep cycle we transition from awake state to drowsiness and then to unconscious state. In medical terms we call these cycles NREM and REM. The Non Rapid Eye Movement state has 4 stages : 1 to 4 and we move from NREM stage 1 (‘light sleep’ stage – even a slight noise can wake us up) to stage 4 (‘deep sleep’ stage ) in about 60-90 minutes and then transition to REM sleep which lasts a few minutes, although as night goes on REM periods get longer. We dream and are in a physiologically aroused state during REM sleep whereas NREM, particularly after stage 2 is associated with all the benefits known to come from good sleep – boosting of our natural defences and metabolism, repair of our body and release of growth hormones. In a healthy sleep cycle we should be spending about 75-80% of the time in NREM sleep and the rest in REM.

In sleep apnea this beautiful sleep cycle is disrupted which results in lot more of REM sleep associated with increase in blood pressure, heart rate, vivid dreams, restlessness. During apneic episode the body goes into fight and flight mode and this continuous stress is not good for the body. So even though a person with OSA would have slept the whole night, snoring away, but the quality of their sleep tends to be much lower and they tend to have far lower levels of oxygen saturation as compared to normal circumstances. This chronic stress on their body results in tiredness and the need for body to rest during the day. Some people tend to have ‘micro sleeps’ in the daytime, sometimes even without knowing. Such a micronap during driving can have disastrous effects and is probably the greatest worry for someone with OSA.

As I have mentioned a few times already, most of the times the people with OSA don’t tend to know it and may not think that there is a problem. But if they are displaying any symptoms then it’s important to alert them of this possibility and encourage them to discuss it with their GP as there are simple tests such as sleep study to diagnose it and to assess the severity of it. There are also various methods of treatment, again depending on the specific nature of problem causing snoring and the degree of severity of sleep apnea.

Amongst the lifestyle factors which can have a positive impact on management of it is limiting intake of alcoholic beverages, particularly of amounts exceeding the daily recommended limits (as alcohol aids the already over relaxed muscles at the back of the throat to relax further – that’s why people tend to snore more after having a few drinks); smoking cessation; weight control and inculcating the habit of sleeping on side and not on the back.

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