Wednesday, March 13, 2013

The purpose of yawning is to stall sleep

Two score and two years ago, as a medical student, I learnt that the medical science does not know why we yawn.

Yesterday, I came across a patient whose yawning and the accompanying behavior threw some light on at least one of its functions in humans. It was but natural then to Google and see if some whippersnapper had not already arrived at the same conclusion. To my pleasant surprise - for that gives me justification to post my observation - researchers are still in dark as to why we yawn.

The most interesting link was to a New York Times article by Nicholas Bakalar - date Dec. 13 2010. And this is what he had to say : Everyone yawns, but no one knows why. Yawning starts in the womb, and most vertebrate species, even birds and fish yawn, or at least do something of the sort, but its physiological mechanisms, its purpose and its survival value remain a mystery.

My patient is an interesting middle-aged single man who carries the diagnosis of Developmentally Disabled though his intelligence is normal. His pathology which erroneously gives the impression of mental retardation is confined to stuttering, autistic traits, social awkwardness, OCD, occasional chastising hallucinations, and a surplus of rage.

The patient had come to the office all set to enthusiastically embark on his session. But that day I was running unusually late, and this extremely controlling patient, who wants everything on his term, did not like the put-down one bit. And therefore when his turn came, he had nothing to say. In fact within minutes of starting the session he declared that he was all done and ready to leave because he had errands to do.

It was a classic tit-for-tat for making him wait.

When told he cannot leave earlier than his allotted time per rules of treatment, he first felt his bald pate by sliding his open palm over it as if to make sure he was there, then closed his eyes and brought his hand down to squeeze the root of his nose between his thumb and middle finger as if in deep thought, and then wearily opening his eyes began to yawn.

The purpose of his yawning to the trained eye of the psychoanalyst was crystal clear:

it was unequivocally saying: I rather be somewhere else and if I cannot do so by walking out of here I can at least do so by becoming oblivious to you through falling asleep and dreaming of being somewhere else.

But there was more than just an avoidance through sleep. There was also a contrary impulse: a struggle to not fall asleep as well. As if outright sleep would be too contemptuous and would upset the social balance between him and me. And though it looked as if the yawning was to usher sleep its true purpose was just the opposite: to prevent him from doing so.

There was no doubt that the whole behavior taken together was a show of counter-contempt and expression of boredom - if I had been uppity towards the value of his time he too had nothing of worth to tell me either. But yawning by itself was not promoting sleep but activating him to keep awake.

So this observation contradicts the view lay people and many scientists take it as self evident: yawning occurs when we want to go to sleep and no doubt it is there to aid sleep. In reality it is an attempt to halt it.

In my patient's case full blown asleep would have been too defiant, and anyway it was not practical to do so in the middle of the day. So he was trying to stall sleep and the physiological mechanism that was being used to achieve the aim was activation of the yawning reflex.

But how does yawning promote wakefulness?

I think by opening the mouth wide, gulping a huge bolus of oxygen and tensing up the muscles around the face and upper torso, the person [at unconscious level] signals to the brain that "look you got to be awake. It is not the right time or the place to fall sleep." The increase in oxygen supply and the rise in muscle tension sends the message to the neuronal circuits that promote wakefulness that it is time to stiffen and gear up, not cut down on your oxygen consumption and call it a day.

In my patient every yawn was followed by a clear, though brief, increase in alertness. And in those moments of flickering arousal he would look at me with an expression which seemed to say "don't take my rejection too seriously, I still respect you, I am still paying attention to what is happening, you are not boring, look I am trying my best not to fall asleep on you."

But this heroic effort to honor me was contending with the counter impulse to break contact with a painful world which had shown no respect for his time and had undervalued him. The ambivalence on the patient's face was clear: aggression/contempt/disdain for me alternating with the counter-impulse to not push the envelope too far.

Now the New York Times article tells us that the scientists have given up on the theory that yawning occurs to increase oxygen supply to the brain. The argument goes that increased oxygen supply can be more effectively achieved by increasing the rate of breathing.

Perhaps the scientists abandoned the oxygen theory prematurely. For it has some merit. Yawning increases the oxygen supply not on a sustained level, as would be required while exercising, or playing sports, and which would be best achieved by rapid breathing, but a brief bolus of oxygen in to the system could be used as a signal to the brain that it is not time to decrease your oxygen consumption but to continue it at the current level to maintain the waking state.

If the purpose of yawning is to activate some parts of the brain to produce wakefulness, why does the person not become fully awake after a yawn of two? Why do humans go into serial yawning and why it is so infectious?

We have already discussed that yawning expresses an ambivalent state of mind. There are two contrary impulses wanting to find expression together and a compromise is reached in which the boredom and sleepiness alternates with yawning which wants to kick-start re-engagement with the world.

It may not be amiss to add that this re-engagement is psychologically effected by activating some quiescent pleasant memory which is somehow associated with the boring situation/person and may induce a fresh interest in what is going on. And this mechanism is perhaps mediated by dopaminergic neurons.

Why dopaminergic neurons and do I have anything to back up such a speculation?

Well there is a chemical which artificially activates yawning. It is called Apomorphine. Since it is attenuated form of morphine it is a narcotic and promotes sleep. Yet, it is a dopamine agonist, a stimulant, which simultaneously promotes arousal and attention. So the chemical apomorphine seems to be heaven sent to confirm my hypothesis that yawning is like a front that expresses two contrary impulses: withdrawal/sleepiness and struggle to maintain wakefulness. And from my previous entries in my blog, specially on the matter of addiction and ADHD, we know that dopamine is a neurotransmitter whose main purpose is to repeat experiences of satisfaction [produce stereotypy of pleasant behavior]. So the release of dopamine in a yawning person is to stimulate pleasant past associations with the current situation/person and reawaken new interests.

Yawning is catchy because if one person signals that I am bored and I have to yawn to keep my focus on you then others counter it by sending the same signal back - you are not worth my attention/wakefulness either. It is similar to how children handle insults. If a child tells somebody that you are a liar, you can count upon getting an immediate retort: "And you are another."

But imitation of yawning may not necessarily be a retort. In a group if one person finds the situation/ surrounding boring and yawns then others follow suit as if to lend support to him: "yes, yes, we second your feelings. What is happening here is not worth our attention either." Here it is more following the leader than tit-for-tat.

Yawning as an expression of disdain as well as an attempt to not make the contempt too blatant was first driven home to me a long time back when I was being ousted as the Acting Chief of Psychiatry at the VA hospital Allen Park. Having brought too many changes too soon and never the one to mince my words when expressing contempt of superiors if they were on the wrong or foolish, I was being stripped off the post.

And the ousting took place in a board room where a bunch of doctors were assembled. They were all tense as the Chief of Staff started reading to me the riot act. The tension was palpable because they expected a spirited comeback on my part. But to their surprise and mine as well, I had hard time keeping my eyes open to what was being said. I found their anger towards me stupid, and knowing that protest was useless, and the whole affair not worth even paying attention to for my fate was sealed, I had tough time keeping awake, and that is what must have triggered the yawning reflex. For I yawned with abandon. And I could not help but notice that the pain of getting dressed down and stripped of the post would temporarily abate while I would be tensing the muscles of chest and my face for the act of yawning. As if that muscle tension was discharging the aggression towards the people who were harming me and consequently generating sensation of pleasure.

Is there any condition where yawning occurs pathologically?

Yawning is a prominent symptom of narcotic withdrawal. Along with diarrhea, muscle and abdominal cramps, runny nose, sweating, tremors, irritation, anxiety, goosebumps there is yawning. Yawning in severe withdrawal can happen every couple of minutes.

One of my patients reported that when she is withdrawing from narcotics she yawns continuously. She gave the following explanation for doing so. Her withdrawal is always marked by high anxiety which turns into nightmares and cold sweats when she falls asleep. So sleep becomes a dreadful and frightening affair which causes insomnia. However, one part of her mind tired from days of abuse and pressured living craves for rest. So the tug-a-war between keeping awake out of fear of dreaming dreadful things and the wish to sleep out of exhaustion sparks the yawning.

She added that only other way to combat sleepiness besides yawning for her is to get absorbed and keep the mind super active with something like cleaning the house or going back to her job as a waitress and make some money. Now both these activities obsessively cleaning house and feeling good about working and making tips are pleasurable activities which secrete dopamine. She reported that yawning also results in a slight improvement in her mood. While yawning her dysphoric feelings abate, though only while she is stretching and tensing the muscles and there is a definite feeling of pleasure though very slight in intensity. In her case yawning is interchangeable with other pleasurable activities and all of which are mediated by dopaminergic neurotransmission.

The original physiological purpose of yawning appears to be part of the orchestrated neurodevelopment which no doubt occurs as a sequential activation of one part of the brain after another. Yawning may play a role in this complex activity through activation of motor neurons which tense the muscle around the mouth and upper torso. This tensing of muscles perhaps releases dopamine which may play a role in making bridges between already active neuronal circuits with freshly activated ones. This physiological reflex which evolved for neurodevelopment appears to have found a side purpose in humans to signal boredom, express contempt and counter the impulse to go to sleep.

ps 3-13-13 Today I saw a patient who once again confirmed by hypothesis that yawning developed as a mechanism to stall sleep. This young man is not getting along with his girlfriend. In the session when he broached this issue within a short time he was flooded with painful emotions and instead of going further with what he had to tell he indulged in a giant yawn. From his expressions I could not help but notice that as soon as his conflict with his girlfriend emerged in his consciousness he first tried to talk about it but as the pain associated with the memory followed in to consciousness he lost interest in the talking and tried to withdraw in to sleep where he could turn the painful memories into pleasant ones through the mediation of dreams but on realizing that it would be not appropriate to fall asleep in front of me he yawned to activate the neuronal circuits connected with wakefulness.  

ps. In the Wall Street Journal 7-16-2013 I read a small write up titled "Why you may yawn less in the summer." It quoted a study which conducted an experiment with two groups of people. One in early summer and the other in winter. They were made to look at pictures of yawning and encouraged to talk about their own yawning behavior. It was found that people were more likely to yawn during winter than early summer months. The reasoning given was that in winter yawing would reduce the brain temperature more. This is not a joke. The study was published in impressive sounding Frontiers in Neuroscience so it got to be true. Yet the question arises why would anybody want to reduce his or her brain temperature especially in winter when you would want to conserve heat. The article claimed in summer the outside temperature was closer to body temperature so the cooling effect was not as robust as during the winter so there was less benefit from yawning.

Now my own experience is that in  uncomfortably hot weather too the tendency to yawn increases. And the explanation may be simpler. When it is uncomfortably hot in the present then a person wants to go to sleep so he can dream of being in the Alps or better still on the peaks of Himalayas. If one is in cold weather the desire to go to sleep and conserve energy is even stronger. So whenever one is in unpleasant surroundings one way to escape from it is to go to sleep. But if it inappropriate to fall asleep in the situation then the yawning mechanism kicks in to activate the wakefulness centers of the brain. Since cool air is a sharper stimulant than air that is nearer to more comfortable temperature it acts as a sharper arousing agent and is gulped in larger quantity through yawning. 

4 comments:

  1. As I read this post, I intentionally yawned, several times to see if, it awakened me to finish reading and taking your comments seriously. After pulling out Webster's and Dorland's dictionaries to help me decipher terminology what you wrote makes sense to me. It amazed me to think and experience, what that small volumne of air can so effectively produce, mental energy and alertness. I understand breathing techniques for yoga and meditation but who would think yawning produces a similar effect.

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  2. Excellent comment. Beautifully put. And best of all it supports the contention that yawning is a way to boost mental energy and produce wakefulness.

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