Learning to laugh
Laughter is an essential human phenomenon. Smiling in response to pleasant physical conditions occurs in early development, usually in the first month of life. As a motor reflex, laughter is usually present by the time a child is 4 months old. By the age of eighteen months, a child smiles once every six minutes, and by four years of age, the rate increases to one smile every one and one-third minutes. The ratio of laughs to smiles increases from one laugh to every ten smiles as eighteen months to one every three smile at four years. The individual differences in the rate of both laughing and smiling become greater as the children grow older. (Stearns, 1972) The instinctual development of smiling and laughing occurs very early in life, suggesting a high level of importance.
What is laughter?
The physiological definition describes laughter as "a successive rhythmic spasmodic expiration with open glottis and vibration of the vocal folds," or "as a series of spasmodic and partly involuntary expirations with inarticulate vocalizations. . ." These dictionary definitions emphasize a rhythmic and spasmodic expiration. While this is true, the motivations for it and its aftermath are much further reaching.
Why do we laugh?
There have been many theories over the years as to why we laugh. Freud suggested that during laughter, you discharge pent-up psychic energies. In a theory by V.S. Ramachandran, we laugh to alert others in the social group that an anomaly, whatever it is we are laughing at, is inconsequential. For example, if someone falls and is not hurt, we laugh to signal to others that the person is all right. The theories vary greatly, but there are so many attributes to the phenomenon of laughter that it is difficult to formulate an all-inclusive theory. Therefore, we take a closer look into this event.
The causes of laughter can be divided into three main groups. One manifestation is laughter as a reflex, such as due to ticking. Another is as a psychosomatic response prompted by a specific stimulus. This is an informative stimulus such as a word, sentence, gesture, action, recollection, situation, etc. This requires the involvement of perception, learning, and memory. This reaction may or may not be terminated voluntarily. The third is again a psychosomatic response, but is differentiated because it is not caused by an adequate informative stimulus and can be terminated voluntarily.
Within this categorization, there are different types of laughter: mirthful laughter, pathological laughter, etc. Mirthful laughter, a lesser studied, but highly interesting type will be the focus of this discussion. A commonly held belief is that mirthful laughter and humor result in positive physical, psychological, and social fitness. With such a expansive area of influence, it is difficult to understand how such laughter influences the body.
Laughter in healing
Studies of the physiology of mirthful laughter, scientifically known as gelotology, are a fairly recent phenomenon. Descriptions of convalescence through positive emotional states have renewed interest in the healing potential of mirthful laughter. Norman Cousins' accounts of the therapeutic effects of laughter during his treatment and recovery from ankylosing spondylitis added to the vast reservoir of anecdotal claims regarding the health benefits of a positive emotional state. (Cousins, 1989 as cited in Wooten, 1996) Cousins, as a result of his experience, formed a humor research task force in order to pursue studies of this connection. As a result of this renewed interest, a variety of experiments have been preformed in order to examine the physiological changes and ramifications that result from mirthful laughter.
Experimental Findings
One such experiment was performed at the college of William and Mary in Williamsburg, Virginia. Here, Derks elucidated the unique pattern of brain wave activity via electroencephalograms during the perception of humor. He found that during the set up to the joke, there was activity in the cortex's left hemisphere. This is where the brain begins its analytical function of processing words. Shortly afterward, most of the brain activity moved to the frontal lobe. This is the center of emotionality. An instant later, activity spreads to both the right and left hemispheres as the right hemisphere's synthesis capabilities joined with the left's processing to find the pattern and "get the joke." A few milliseconds later, before the subject laughed, the increased brain wave activity spread to the occipital lobe. This area of the brain processes sensory information. The increased fluctuations in activity reached a peak and crested as the brain "got" the joke and the external expression of laughter began. (Derks, 1992) These findings show the involvement of many areas of the brain in response to a humorous stimulus.
In line with this finding, Fried and Wilson found that electrical stimulation in the anterior part of the human supplementary motor area (SMA), located in the cortex of the left frontal lobe, stimulated mirthful laughter. In each case of stimulation, the patient attributed the laughter to an external stimulus such as people in the room, but it occurred at precisely the moment of stimulation. Also, the duration and intensity of laughter increased with increasing stimulation, ranging from a smile to robust laughter. (Fried and Wilson, 1998) This shows that at least part of the pathway runs through the cortex of the left frontal lobe and that the pathway can be triggered by external stimulus. Moreover, the patient's identification of an external stimulus speaks to the point at which this area exists in the pathway. This may open the door for more specific research done on either the mechanism of laughter, or the results of such a burst.
Further research explored the effects of laughter on muscle tone, respiration, and the cardiovascular system. The initial effects of laughter are stimulatory. This includes an elevated pulse, heart rate, and blood pressure. Laughter also increased respiratory rate, ventilation, and accelerates the change of residual air. Cessation is followed by a brief relaxation phase. Muscles involved in laughter undergo slight contraction while those not involved are flaccid. Muscle tone in the latter was found to diminish during laughter (Paskind, 1932). This relaxation helps ease muscle tension. Exertion of the expiratory muscles and change in the intrathoracic pressure activate both a muscle and respiratory pumping system that accelerates the return of venous blood to the heart, reducing vascular stasis.
Another mechanism by which mirthful laughter benefits health is the enhancement of the immune system. There have been many studies done elucidating the immunosuppressive effects of stress. As a corollary to this phenomenon, laughter may function as a modulator of the classical stress response, reducing immunosuppression. It may, however, function independently.
Mirthful laughter influences different aspects of the immune system. One effect has been observed in the body's concentration of salivary immunoglobulin A (IgA). Salivary IgA constitutes the body's first line of defense against entry of infectious organisms through the respiratory tract. It was found that IgA concentration increased significantly in ten subjects after viewing a humorous video (Dillon and Baker, 1985). These levels declined, however, minutes after viewing. No significant change in IgA concentration was noted for the control group. This suggests that there is a temporary immune boost as a result of humor.
Also, in the same study, scores on a questionnaire measuring the perceived use of humor as a coping skill were positively related to initial IgA concentration, but did not decline as did the IgA concentration after the video. This implies that the incorporation of humor into everyday life as a coping style may have long term immune system benefits.
Another study suggests that mirthful laughter favorably effects rheumatoid arthritis (RA) symptoms. Patients with RA and healthy controls were exposed to "Rakugo," a traditional Japanese comic story. There was a significant reduction of serum IL-6 levels in the patient group after exposure to mirthful laughter. Supporting this correlation, there is recent evidence that monoclonal antibody against IL-6 receptor is effective in the treatment of RA. (Nakajima, Hirai, and Yoshino, 1999)
Laughter is also thought to have an effect on the activity of Natural Killer (NK) cells. NK cells are phagocytes that engulf viral or cancerous cells. In this case, however, the studies have produced conflicting results. Research shows reduced levels of NK cell numbers and activity in patients undergoing stress. (Wooten, 1996) The corollary, which suggests that levels would increase in a positive emotional state, has not been supported. In fact, a study that measured the immune responses caused by both "stress" and "humor" in the same patients showed a decrease in the NK cell activity induced by the humorous video. (Kamei, Kumano, and Masumura, 1997)
Laughter is also thought to effect the endocrine system. It appears to reduce serum levels of cortisol, dopac, epinephrine, and growth hormone. In stress inducing experiments, the change in IgA levels following the stress are significantly related to those of norepinephrine. The implications of a change in endocrine hormone levels due to laughter are extensive. This enables laughter to effect any and all parts of the body.
For example, during stress, the adrenal gland releases corticosteroids that are converted to cortisol in the bloodstream. Cortisol, which increases with stress response, inhibits mechanisms such as IL-2 gene expression and proliferation of lymphocytes in vitro and in vivo. (Berk, 1988) Positive emotional activities such as mirthful laughter have been suggested to reduce the classical stress response. A moderating effect, such as humor, would lessen sympathetic stimulation due to stress and, as a result, might lessen the impairment of the immune system. Berk's experiment found that cortisol levels in humor subjects decreased significantly during and after viewing the video, while spontaneous lymphocyte blastogenesis significantly increased concurrently. (Berk, 1988)
The effect of laughter on the central nervous system is not well known. There is an increase in catecholamine levels. Current theories suggest that this may effect mental functions such as increasing interpersonal responsiveness, alertness, and memory. (Fry, 1992)
These experiments are just the beginning in the newly developed field of psychoneuroimmunology. As a rapidly developing field, it explores the interactions between the central nervous system and the immune system. Studies have documented the autonomic innervation of the lymphoid tissue, both in the vasculature and in the paryenchymal areas close to the lymphocytes. Moreover, there is evidence that lymphocytes contain adrenoreceptors on their surfaces and their responses are affected by neurotransmitters. (Halley, 1991) This anatomical connection links the brain and the immune system, allowing for communication. Another finding suggests the existence of a chemical connection. This data shows that immune cells have receptors for and produce the same neuropeptides that are found in the brain and other glandular tissues. (Pert, Ruff, Weber, and Herkenham, 1985)
Research also shows that this communication may be bi-directional. One study shows that after immune system activity is increased, there is increased hypothalamic neuronal activity. (Besedovsky, Rey, and Sorkin, 1985) This relationship, once elucidated, has amazing potential for practical application.
Studies such as those mentioned throughout this paper, however, are complicated by numerous variables. The likelihood of confounding factors increases greatly in dealing with any psychological factors. As a consequence, studies will conflict and it may take quite a time to put together a cogent theory explaining these complicated phenomena.
Most questions remain unanswered. What is the relationship between laughter and learning? How does that work in a physiological level? What causes the contagious nature of laughter? Why does a hearty belly laugh feel good? Is it just a release of tension, or could it be operating through another pathway? At this point, there is just not enough research done on the subject to attempt to answer these questions. And in any such void of information, the few connections that are made give rise to exponentially more questions.
Clinical uses of laughter
The details of the communication between the mind and body, however, are not necessary to begin using the link as it relates to healing. As a result, mirthful laughter is used in practice for its therapeutic effects. Laughter therapy has been used successfully during psychotherapy of elderly patients in deep depression and or suicidal disappear. Such therapy is based on the principle that humor is life affirming, increases cohesion within groups, is interactive, and is stress reducing. While the discussion of its influence is on the psychological aspects, we now know that there are beneficial physiological consequences of such therapy.
Laughter is also useful as a form of activity for bed-ridden patients. It provides a light workout for those muscles involved. A large mass of muscle tissue participates, producing a total body response that provides some conditioning exercise.
Laughter has also been adopted in therapy for chronic respiratory conditions. It increases ventilation and aids in clearing mucus plugs. It also accelerates the exchange of residual air, increasing blood oxygen levels. (Fry, 1992)
Laughing meditation is another practice that has been found to be therapeutic. It is simply a meditation exercise that consists of three stages. The first stage is stretching, the second is laughing and/or crying, and the third is silence. The emphasis of this sort of meditation is to enhance the ability to cope with life by accepting it. Such meditation functions to relieve stress on both a psychological and physiological level.
Mirthful laughter and more generally, a positive emotional state, show tremendous influence on one's physical state. While the research does not specify whether it is laughter or the general positive state of mind that produces results, clinical practice could benefit from exploring other methods of creating such a positive mental state. Options include other forms of meditation, hypnotherapy, social activity, pharmacological methods, etc.
Final Thoughts
Such therapies have been instituted and utilized long before the advent of direct scientific support. For ages, people have been aware of a mind-body connection and have used it in healing techniques. Only now, however, is the research community recognizing the potential of such a connection. This dynamic relationship allows for a bi-directional flow of information, allowing one to tap the system in any location and produce widespread effects.
It also allows for the manifestation of physiological change as a result of conscious thought. Science has finally caught up with the long-standing belief of mind over matter. We have seen this incorporated in common culture throughout the ages, from ancient forms of meditation, to Shakespeare's declaration that "thinking makes it so." The world of science has now come to the first step of a long search. A result of such a search is to be able to physiologically manifest one's own thoughts with consistency and accuracy. The prospect of such a power accessible to everyone is incredible. Such a step will revolutionize the way in which people relate to their bodies. With such power in the hands of individuals, medicine would take on an entirely different role in our society.
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