My greetings to all,

My name is Geoff and I am new to this forum. I'm an automotive engineer by profession, but I have had the good fortune to be introduced to the medical world by catching Parkinsons Disease. I had a maternal grandmother with PD, but I also grew up on a farm on a Parkinsons Road - so the jury is out as to whether the cause is genetic or environmental...

This is a long post. But I have recently experienced some weird episodes that have made me think deeply about neurology, PD and the yawning reflex.

Up front - I think the act of yawning and stretching might be a whole body neurological event, possibly to recalibrate the brain to deal with changing muscle condition. When I yawn deeply, my Parkinsons gets better.

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I am 48 years of age and have Parkinsons Disease. I have had it for six years and it has advanced rather quickly in recent months. As a quick bit of background, to me it is a condition where I have tremors and I struggle to initiate movement. At its worst, I get to the point where I feel completely locked into my body.

Now I am a mechanical engineer by training, and I have a reasonable understanding of the principles of dynamic systems and control theory. Whilst I struggle with the mathematical side of it, I’ve got a good feel for how a control system can be seen as an incrementally stepping feedback loop - where a signal is given to initiate a desired motion, the motion is then measured by some form of sensor, an “error” is calculated between desired and actual motion, and then a processor reads the error and sends a corrective signal to alter the motion accordingly.

So I was quick to notice that PD is a failure somewhere in my onboard “control systems”. My body gets confused by the signals it receives, and gets lost somewhere in the feedback and processing loop. I lose balance, and the various lever mechanisms in my body can go into tremor – which is classic resonance “overshoot / overcompensate” behavior of a dynamic system out of whack.

Now there are all sorts of misleading descriptions of the symptoms, including that we suffer “muscle stiffness” and “muscle weakness”. I am told this by many “experts” who have spent years observing the disease, but not actually FEELING the disease.

The stiffness thing is actually a bit wrong. My muscles FEEL stiff, but they don’t actually get stiff. As in, when I get “locked in”, I feel a pain in my muscles that feels like they are under tension, but when the paramedics have picked me up, my body is completely limp.

What it feels like to me is that signals are going to my muscles to initiate motion – a light pre-tension to prime them to get ready to do something – but the muscles don’t seem to then know which way to go. It is like they are buzzing with low level contractions that aren’t big enough to initiate movement. They are priming – but then not getting the next signal to go. The system is “lost”.

In recent weeks I have noticed some rather bizarre correlations – curiously, relating to yawning .

•When I yawn and stretch, the part of me that is stretched stops tremoring and comes under control.

•What’s more, when I am waiting for my levadopa drug to “kick in” on each of my medication cycles, I get to a point where my hands and feet start to tingle and then this is followed by the urge to yawn and stretch. If the yawn and stretch is a good one, then suddenly I am “ON” and I can jump out of bed and bound into the day.

•When I try to initiate a movement and cannot do it, my body often tries to stretch the offending body part to its full extremes of motion, and I feel the desire to yawn.

•When I have a medication cycle that doesn’t kick in properly, I fall into this succession of unsatisfying yawns – as if my body is saying “that one didn’t work – try again”.

Now I am in hospital right now, and I have been asking the various medicos what the purpose of yawning is. No-one seems to know. I am going to propose this:

•A good yawn, and subsequent full body stretch, is the body’s morning calibration check. It is sort of like the self-diagnostic and movement check that for example your computer printer goes through when you turn it on.


Now the body is a delicately balanced system of levers (bones) pulled by contracting actuators (muscles). The muscles are activated by the neurological system controlled by a processing unit (the brain). If for example we wish to control our lower arm movement, we need to learn the relative tensions in the biceps and triceps to establish equilibrium, and thus the brain needs to learn the signal strength it needs to send to each of the muscles.

But the muscles themselves change with time. They get stronger or weaker depending on damage, use, health etc. So the body needs to undergo regular recalibration checks. Potential procedure to do so – lightly tension opposing muscles (e.g. biceps/triceps), and register in brain the relative signal strengths required for equilibrium – preferably at some repeatable datum point (e.g full stretch or full contraction).

What do we do when we yawn? We slowly stretch muscles to their extension and contraction limits, apply a light tension to them, and repeat this for a succession of muscle groups throughout the body. We think of yawning in terms of it being a breathing / throat-based event of sorts, but to me it is simply the first muscle system that we are testing. If we indulge in the full yawn, we can feel the stretching/tensioning tests progressing from throat to face to chest, torso, arms and maybe even legs. If yawning was a breathing event, why would it progress to legs and arms?

So why does the yawn and stretch process occur in a range of animals and not just humans. All animals with neurological systems would need a regular recalibration of the system. Why start with the throat? Well, I am thinking this. The throat is the closest muscle system to the brain stem, and the first branches of the nervous system are around the face/throat area. The brain stem is where dopamine is generated.

Maybe dopamine initiates the “full body system muscular calibration check”. It initiates it firstly in the closest muscle system, the throat. Once that system is checked, the rolling calibration check moves through the mouth, the neck, torso, shoulders, arms, legs etc.

The theory seems to explain some stuff about yawning that scientists have yet to explain properly. Contagious yawning? Well, if your competitor in the game of life is recalibrating and fine-tuning their neurological system to beat you to that tasty rabbit that is running past, you had better do the same. Athletes yawning? Fine-tuning themselves for the race.

So my condition, with its lack of dopamine, has trouble running the calibration check. It certainly feels like it. It feels like my body system wants to move, and can move, but does not really know where it is at relative to its datum points. It is lost.

In recent days, I have on a number of occasions (but not every time) managed to "snap" myself from an uncoordinated state to fully "on" in minutes. Medication did assist.

I’m pretty excited about this. I asked the physio here if he could look up links between yawning and dopamine. He came back five minutes later with news of a heap of search results, and in the paper he gave me dopamine was the first chemical mentioned. But the yawning event itself remained unexplained. It seems the link is there – but it seems no-one knows why.

If a bodily function is semi-unconscious, seems to be initiated in the brain stem, and is repeated behavior across species, I have a feeling it is more significant than a signal that we are a bit sleepy.

I haven’t been particularly scientific about this thus far, but it certainly seems interesting and promising. I am formulating some ideas on how to pull this together into some sort of study or even a potential PhD thesis. No-one seems to have come up with a decent explanation of what yawning and subsequent stretching is all about (and I reject the notion of it being about oxygen or carbon dioxide – I can simply breathe more heavily if that was the purpose, and I could do it without getting arms and torso and legs involved.) Viewing the body as a mechanical control system that needs regular recalibration seems to give the yawning process a purpose.

I would be very interested in your thoughts…

Kind regards,

Geoff