Potential Therapeutic Benets of Laughter in Mental Health 243Tohoku J. Exp. Med., 2016, 239, 243-249
Received April 7, 2016; revised and accepted June 27, 2016. Published online July 16, 2016; doi: 10.1620/tjem.239.243.
Correspondence: JongEun Yim, DSc., Department of Physical Therapy, Sahmyook University, Hwarangro 815, Nowon-gu, Seoul 139-
742, Republic of Korea.
Therapeutic Benets of Laughter in Mental Health: A Theoretical
1Department of Physical Therapy, Sahmyook University, Seoul, Republic of Korea
In modern society, fierce competition and socioeconomic interaction stress the quality of life, causing a
negative inuence on a person’s mental health. Laughter is a positive sensation, and seems to be a useful
and healthy way to overcome stress. Laughter therapy is a kind of cognitive-behavioral therapies that
could make physical, psychological, and social relationships healthy, ultimately improving the quality of life.
Laughter therapy, as a non-pharmacological, alternative treatment, has a positive effect on the mental
health and the immune system. In addition, laughter therapy does not require specialized preparations,
such as suitable facilities and equipment, and it is easily accessible and acceptable. For these reasons,
the medical community has taken notice and attempted to include laughter therapy to more traditional
therapies. Decreasing stress-making hormones found in the blood, laughter can mitigate the effects of
stress. Laughter decreases serum levels of cortisol, epinephrine, growth hormone, and 3,4-dihydrophenylacetic
acid (a major dopamine catabolite), indicating a reversal of the stress response. Depression is a disease,
where neurotransmitters in the brain, such as norepinephrine, dopamine, and serotonin, are reduced, and
there is something wrong in the mood control circuit of the brain. Laughter can alter dopamine and
serotonin activity. Furthermore, endorphins secreted by laughter can help when people are uncomfortable
or in a depressed mood. Laughter therapy is a noninvasive and non-pharmacological alternative treatment
for stress and depression, representative cases that have a negative influence on mental health. In
conclusion, laughter therapy is effective and scientically supported as a single or adjuvant therapy.
Keywords: alternative treatment; depression; laughter; mental health; stress
Tohoku J. Exp. Med., 2016 July, 239 (3), 243-249. © 2016 Tohoku University Medical Press
Recently, there has been increased interest in noninva-
sive and non-pharmacological therapy. Laughter therapy in
the media has grown and many researchers have conducted
a variety of studies on laughter (Cho and Oh 2011).
Moreover, as laughter therapy does not require specialized
preparations such as suitable facilities and equipment, is not
prohibited by cost, does not depend on when or where it
happens, and is easily accessible and acceptable, the medi-
cal world has also introduced it into treatment programs
(Mora-Ripoll 2010; Ko and Youn 2011). Laughter therapy
physiologically reduces the level of stress hormones,
increases the level of health promoting-hormones such as
endorphins, and strengthens the immune system by increas-
ing the number of T-lymphocytes through activation of nat-
ural killer cells, which multiplies white blood cells in the
body, and Ig A, G, and M, which raises immunity in the
body (Bennett and Lengacher 2006; Hayashi et al. 2007;
Bennett and Lengacher 2009). In addition, it also has an
effect of reducing blood pressure by controlling vasocon-
striction by lowering the degradation of the vasorelaxant
substance, nitric oxide, and reducing cortisol thus raising
blood sugar (Bennett and Lengacher 2008; Hasan and
Hasan 2009). As for the mental effects of the laughter ther-
apy, it helps reduce unpleasant feelings such as tension,
anxiety, hatred, and anger, alleviates stress and depression,
aids better interpersonal relationships, and improves insom-
nia, memory failure, and dementia (Takeda et al. 2010; Ko
and Youn 2011; Bains et al. 2015).
In modern society, high levels of stress are caused by
erce competition and socioeconomic stressors. As this
stress has a negative impact on self-esteem, which affects
quality of life and personal motivation, it increases depres-
sion and leads to a harmful inuence on a person’s mental
health. Furthermore, a potential mental health problem
may lead to the affected person having many difculties in
maintaining a good lifestyle at home and work life (Bast
and Berry 2014). Moreover, there are many problems
related to the elderly in society due to the nature of an aging
society. In particular, problems regarding the mental health
of elderly people are being magnied. Depression, second-
ary to loneliness and physical discomfort due to aging, is a
most important emotional problem in old age and requires
social attention and positive intervention. In addition to
depression, another remarkable change in the mental func-
tion of the elderly is the loss of intellectual ability (Takeda
et al. 2010; Ko and Youn 2011). This disorder of cognitive
function can put a high burden on a person, their family,
and society as a whole. The patient, and their family, can
suffer from physical and psychological stress. Laughter, as
part of the solution to these mental health problems, might
provide a desirable noninvasive and non-pharmacological
therapy that restores their happiness, by making the human
body and soul healthy, and improving quality of life and
Laughter is a physical reaction seen in humans and
some other species of primates, consisting typically of
rhythmic, often audible, contractions of the diaphragm and
other parts of the respiratory system. It is a response to cer-
tain external or internal stimuli. Laughter can arise from
activities such as being tickled, or from humorous stories or
thoughts (Stearns 1972; Schultz and Horibe 1974). Most
commonly, it is considered the expression of a number of
positive emotional states, such as joy, mirth, happiness,
relief, etc. On some occasions, however, it may be caused
by contrary emotional states such as embarrassment, apol-
ogy, or confusion, for example, nervous laughter. Age,
gender, education, language, and culture are all factors as to
whether a person will experience laughter in a given situa-
tion (Omwake 1937).
Dr. Miletus in the 4th century said, Laughter is gelos in
Greek, and the root of this word is Hele, which means
Health.; philosophers in the 16th century, Laughing is also
like taking physical exercise.; Kant in the 18th century,
Laughter has a great inuence on keeping balance in physi-
cal health.; Spencer in the 19th century, Laughter helps ease
tension and recover health (Dean and Gregory 2004;
Hyeong Woo 2010). The word, laughter, comes from
‘hliehhan’ in Old English. The word imitated sounds of
laughter. Laughter might be represented by the regular con-
tinuation of syllables made with short vowels such as “ha-
ha”, “ho-ho”, and “he-he” in English. Laughter is also a
general feature of people that occurs instinctively when
socially talking to each other (Provine 2000). Laughter is
the expression of one’s joyful heart or feeling when their
desire is satised; it can be a spontaneous expression of
their emotion when they have a joyful feeling or heart,
physical stimulus or pleasure, or a heart or feeling physi-
cally arousing when they feel ridiculous of an odd word,
behavior or appearance. It can also be a phenomenon of
expressing a heart or feeling that shows one’s pleasant men-
tal activities; it physically shows the working of one’s own
mind and the state of their consciousness.’ Laughter is
laughing pleasantly, briskly, and loudly, and it is a natural
phenomenon that happens in reaction to one’s senses or
heart, or to a word or behavior that makes another laugh
(Bennett and Lengacher 2006).
There are three categories in the theories of laughter:
arousal, discrepancy, and superiority (Apte 1985; Lefcourt
and Martin 2012). First, the arousal theory is concerned
with the cognitive aspects of laughter; stress increases
arousal, while laughter is able to reduce stress by easing
arousal and tension. This theory says if people laugh in a
stressful situation their physical arousal state declines and
the stressful situation is no longer as negative or detestable.
That is to say, the theory suggests that laughter shows a
complicated interaction of mind and body between cogni-
tion and emotion, rooted in the brain and nervous system.
Freud (1928) also considered laughter as a mechanism that
can block the attacks of another, and stated that it reduces
negative emotional responses or unpleasant feelings (Freud
1928). Second, discrepancy theory is concerned with the
cognitive aspect, which says laughter starts from the dith-
ered process, situation, or thought apart from the knowledge
or logic that people commonly know. This theory says peo-
ple laugh when they realize there is discrepancy between
the actual situation and their general knowledge of it. The
theory has a viewpoint emphasizing logical, linguistic, and
cognitive aspects. Laughter happens at the moment misun-
derstanding and bewilderment arouse in communication,
deviating from the smooth course of the cognitive process.
Laughter occurs at the moment cognitive imbalance — that
is, the point of discrepancy or disharmony — disappears
and balance recovers. Laughter at this moment is an
expression of pleasant enlightenment. According to the dis-
crepancy theory, people can laugh not only when they meet
something different from their expectation but also when
they meet something in discord with their expectation
(Keith-Spiegel 1972). Third, the superiority theory says
that laughter occurs when people look down on others more
than who they are actually, or when they have a feeling or
thought that they are superior to others. The theory says
laughter restricts the external environment and raises con-
dence (MacGhee and Pistolesi 1979). By raising content-
ment without going against the grain, laughter allows peo-
ple to take adequate action against stress and increases
condence (Martin 2010).
Categories of Laughter
Five large categories can be summarized from a medi-
cal and therapeutic point of view: (1) genuine or spontane-
ous laughter; (2) simulated laughter; (3) stimulated laugh-
ter; (4) induced laughter; and (5) pathological laughter
(Table 1). Spontaneous laughter, unrelated to one’s own
free will, is triggered by different (external) stimuli and
positive emotions. It has been reported that spontaneous
Potential Therapeutic Benets of Laughter in Mental Health 245
laughter causes typical contractions of the muscles around
the eye socket (Ekman et al. 1990). Simulated laughter is
triggered by oneself at will (self-induced), with no specic
reason (purposeful, unconditional), and therefore not elic-
ited by humor, fun, other stimuli, or positive emotions.
Stimulated laughter happens as a result of the physical con-
tact or action (reex) of certain external factors (i.e. to be
ticklish, specific facial or bodily motions, by pressing
laughter bones) (García-Rodera 2007). Induced laughter is
a result of the effects of specic drugs or substances (i.e.
alcohol, caffeine, amphetamines, cannabis, lysergic acid
diethylamide or LSD, nitrous oxide or ‘‘laughing gas’’, and
more). Lastly, Pathological laughter is secondary to inju-
ries to the central nervous system caused by various tempo-
rary or permanent neurological diseases and may also occur
with certain psychiatric disorders. Pathological laughter is
developed with no specic stimulus, is not connected with
emotional changes, has no voluntary control of its duration,
intensity or facial expression, and sometimes comes with
‘‘pathological crying’’ (Wortzel et al. 2008).
Physiological and Psychological Effects of Laughter
Laughter has numerous effects involving the muscular,
cardiovascular, respiratory, endocrine, immune, and central
nervous systems (Table 2). The effects of laughter on cer-
tain physiological outcomes are as follows: laughter (1)
exercises and relaxes muscles, (2) improves respiration, (3)
stimulates circulation, (4) decreases stress hormones, (5)
increases the immune system’s defenses, (6) elevates pain
threshold and tolerance, and (7) enhances mental function-
Table 1. Main characteristics of ve large categories of laughter.
Spontaneous laughter Unrelated to one’s own free will, is triggered by different (external) stimuli and
Is triggered by oneself at will (self-induced), with no specific reason (purposeful,
unconditional), and therefore not elicited by humor, fun, other stimuli, or positive
Happens as a result of the physical contact or action (reflex) of certain external
factors (i.e. to be ticklish, specific facial or bodily motions, by pressing laughter
Is a result of the effects of specific drugs or substances (i.e. alcohol, caffeine,
amphetamines, cannabis, lysergic acid diethylamide or LSD, nitrous oxide or
‘‘laughing gas’’, and more).
Is secondary to injuries to the central nervous system caused by various temporary
or permanent neurological diseases and may also occur with certain psychiatric
Physiological outcomes Psychological outcomes
•Exercises and relaxes muscles
•Decreases stress hormones
•Increases the immune system’s defenses
•Elevates pain threshold and tolerance
•Enhances mental functioning
•Reduces stress, anxiety, and tension, and
counteracts symptoms of depression
•Elevates mood, self-esteem, hope, energy,
•Enhances memory and creative thinking
•Improves interpersonal interaction
•Increases friendliness and helpfulness
•Promotes psychological well-being
•Improves quality of life and patient care
•Intensifies mirth and is contagious
Table 2. Physiological and psychological effects of laughter.
ing (Martin and Lefcourt 2004; Sahakian and Frishman
2007; Ripoll and Rodera 2008).
The psychological effects of laughter relate primarily
to both its use as a coping mechanism and, to a lesser
extent, its enhancement of interpersonal relationships. The
research reviewed in this area, greater in volume and
strength than the evidence for physiological health benets,
can be summarized as follows: laughter (1) reduces stress,
anxiety, and tension, and counteracts symptoms of depres-
sion; (2) elevates mood, self-esteem, hope, energy, and
vigor; (3) enhances memory, creative thinking, and problem
solving; (4) improves interpersonal interaction, relation-
ships, attraction, and closeness; (5) increases friendliness
and helpfulness and builds group identity, solidarity, and
cohesiveness; (6) promotes psychological well-being; (7)
improves quality of life and patient care; and (8) intensies
mirth and is contagious (Scholl and Ragan 2003; Gelkopf et
al. 2006; Arminen and Halonen 2007).
Laughter therapy is a kind of communication that
arouses laughter, smiling, pleasant feelings, and enables
interaction. Laughter therapy uses laughter for the purpose
of treatment to promote leading a desirable life, by keeping,
recovering, and preventing physical, psychological, social,
mental and spiritual functions through spontaneous and
nonspontaneous laughter (Mora-Ripoll 2010). This is a dif-
ferent approach from general medical treatments; it focuses
on the approach that both body and mind can be healthy
only when the psychological aspects of the brain are
changed, beyond just physical treatment. According to the
American Association for Therapeutic Humor (AATH),
laughter therapy refers to an activity that improves a
patient’s health and welfare using interesting experiences
and expressions. Therefore, laughter therapy can be a series
of cognitive-behavioral therapies that helps make physical,
psychological, and social relationships healthy and ulti-
mately improves the quality of life (Ko and Youn 2011). It
has taken a very long time for laughter to become a recog-
nized medical therapy. Although it started with Hippocrates
and Aristotle, laughter therapy was not again acknowledged
until the 20th century. Norman Cousins in the mid-20th cen-
tury established the effects of laughter in a modern setting
and brought the naissance of laughter therapy. He was the
editor-in-chief of the ‘Saturday Review’ of America.
Cousins suffered from ankylosing spondylitis, and realized
at the age of 50 that he did not feel pain for 2 hours when
he laughed while watching TV comedy programs.
Discovering this fact, he was invited by the California
University Hospital and began to earnestly study the medi-
cal effects of laughter and acknowledged the clinical effects
of laughter. In his book, ‘Anatomy of an Illness’, Cousins
stated ‘laughter is like a bulletproof vest’, and wrote about
the apparently remarkable power of afrmation and laugh-
ter therapy. He later went on to become a professor and
studied the effectiveness of laughter on health, and is often
referred to as the father of laughter therapy (Cousins 1989).
Since then, theses reporting that laughter helps relieve
stress and helps cure illness began to be released and laugh-
ter therapy spread in North America. Over the course of 40
years of study, Dr. William Fry of Stanford University
School of Medicine developed a theory of laughter therapy,
and found that humor and laughter produced natural pain-
killers in pituitary, such as endorphins, improved blood cir-
culation, and decreased stress (Fry and Salameh 1987). In
addition, in 1996 Prof. Lee Berk of Loma Linda University
School of Medicine in California, found that ‘laughter
increases immune globulin 3 times and interferon 200
times’; he found after 18 years of study that natural killer
cells were activated by laughter (Berk et al. 1989b; Berk
and Tan 1995).
Laughter and Stress
Stress became an ofcial term when the Canadian doc-
tor, Hansselye, rst presented a theory of general adaptation
syndrome, based on the results of various kinds of animal
testing (Evans 1982). The root of the word stress is from
‘stringer’ in Latin, which means ‘tighten’. In the 17th cen-
tury, it was used to describe pressure or physical tension; in
the 20th century, stress evolved to mean the psychological
pressure and tension that people receive from the outside
(Ivancevich and Matteson 1980; Sonnentag and Frese
Lazarus and Folkman (1984) considered stress as the
specic relation between an individual and the environment
when people think that a personal resource is lacking and
their comfort is at risk (Lazarus and Folkman 1984). Stress
can be classied into three kinds: stress as a stimulus, as a
response, and as an interaction. First, stress as a response is
interested in the psychological and physiological response
to surroundings; it considers stress a certain response to the
break or change in physiological, physical, behavioral, and
emotional equilibrium or the response trying to maintain
homeostasis in the face of various stimuli. Second, stress
as a stimulus is to receive a stimulus from a special image
or form; it includes various stimuli from the surroundings
such as the external environmental conditions and internal
physiological phenomena. Third, stress as an interaction
consists of the individual’s response to a stimulus from the
surroundings; not only can an individual connect a stimulus
element of the surroundings with a response, but personal
characteristics can also affect the surroundings. From the
interactional perspective, psychological stress can be a cer-
tain relation between an individual and their environment,
which is evaluated to exceed the personal resource and
threatens their comfort (Lazarus and Folkman 1984).
Modern society is composed of numerous stressors.
That nothing can be done without stress means that stress
may be an origin of many illnesses. To sum up the study
results of the medical and psychological world on stress, it
is an indisputable established theory that most of the ill-
nesses mankind develops, at least in part, are due to stress
Potential Therapeutic Benets of Laughter in Mental Health 247
or that stress aggravates the situation. People look for alco-
hol and recreational drugs or use coffee or cigarettes to
relieve stress; however, certain items of personal preference
for stress relief can produce bigger stresses and destroy
One non-medical method of stress reduction is laugh-
ing and being in pleasant environments. Laughter is a posi-
tive sensation, and seems to be a useful and healthy way to
overcome stress. Decreasing stress-making hormones
found in the blood, laughter can mitigate the effects of
stress (Farifteh et al. 2014). A popular theory for under-
standing laughter includes its evolution as a relief of ner-
vous energy, potentially making it an ideal antidote for
stressful situations. This is supported by the empiric obser-
vation that laughter decreases serum levels of cortisol, epi-
nephrine, growth hormone, and 3,4-dihydrophenylacetic
acid (a major dopamine catabolite), indicating a reversal of
the stress response (Berk et al. 1989a). In a previous study,
33 subjects viewed a humorous video and, subsequently,
stress level and immune function (natural killer cell activ-
ity) were recorded. As a result, stress level decreased and
immune function increased in the experimental group com-
pared with the control group (Bennett et al. 2003).
Since 1970, laughter has been regarded as a comple-
mentary and alternative therapy (Cousins 1976). As laugh-
ter is a noninvasive complementary/alternative therapy, the
use of laughter therapy has spread rapidly. Currently, there
are several laughter therapy clubs around the world in
which people gather to practice laughter and laughing on
purpose; this fake laughter gradually becomes effective in
releasing “anti-stress and joyful hormones” (Ghodsbin et al.
Laughter and Depression
The word ‘melancholia’ started to be used by at least
B.C. 400, when Hippocrates rst recorded and described it.
‘Depression’, typically used synonymously with ‘melan-
cholia’, first began to be used when Bleuler (1911)
described it, and that overall depression includes phenom-
ena such as kinetic phenomena occurring as a result of all
mental actions, such as mind, mood, and consciousness that
feels depression, excitement, and satisfaction, or, more
loosely, it refers to the element that occurs to the mind try-
ing to accomplish something and is forcibly oppressed (Ko
and Youn 2011).
Depression has a very high rate of prevalence and is
one of the most common mental disorders. It can be
dened as the depressed state of the pathological level.
That is to say, depression refers to a kind of mental disease
where people are seized by a sense of inadequacy, of isola-
tion, of futility and of guilt and suicidal impulse in a
depressed mood and in demotivation; it is different from a
temporary depressed feeling (Shahidi et al. 2011). A
depressed feeling is an emotional response of being sad,
hopeless, frustrated, or dispirited, which are almost relieved
when situations improve, but depression is a disease, where
neurotransmitters in the brain, such as norepinephrine,
dopamine, and serotonin, are reduced and there is some-
thing wrong in the mood control circuit of the brain. It is a
disease that weakens both mind and body, including physi-
cal symptoms, moods, and thoughts (Cho and Oh 2011).
Specically, when people feel severely down, the symptom
can be called depression. It is termed clinical depression
when pent-up, inactive, and worried feelings continue at
least 2 weeks, not allowing an individual to lead a normal
life. Clinical depression also requires drug treatment; there-
fore, depression needs to be divided into the general
depressed feeling and severe depression. Unlike the tempo-
rary depressed feeling, depression does not vary according
to situation and can continue for years if not cured (Caspi et
Laughter helps people endure stressful processes or
situations, reduces depression, helps people judge their
problems objectively, and improves problem-solving ability
by increasing insight. Therefore, laughter helps people pre-
vents themselves from being inuenced by the environment
and control themselves (Wooten 1996). There is also an
opinion that laughter is a pleasant stress, which means
laughter is a stress that has a positive aspect and gives fresh
and powerful energy. Thus, laughter is used to reduce neg-
ative cognitive responses and relieves stress (Bennett 2003;
MacDonald 2004). It is reported laughter has the best effect
among methods that can relieve stress, and that if we keep
practicing even a forced laugh, our body will react to it and
become more pleased and healthy (Ekman 1984; Lefcourt
and Martin 2012). A positive mood can be gained through
the forced laugh, and a bad mood, personality, or thought
can be changed somewhat into a positive direction (Isen
and Means 1983). According to the latest precedent stud-
ies, reduction in secretion of the neurotransmitters, dopa-
mine and serotonin, is the representative of one of the many
causes of depression; therefore, if the secretion of those
substances reduces, there will be a disorder in mood control
in the brain and depression will develop (Brown and
Gershon 1993). However, a positive attitude and forced
laughter can help maintain dopamine activity (Ashby et al.
1999). Furthermore, endorphins secreted by laughter can
help when people are uncomfortable or in a depressed
mood (Lebowitz 2002). Moreover, in a study on the effects
of laughter therapy on depression in middle-aged women
and their blood serotonin concentration, blood serotonin
concentration showed the lowest result in the group with
the severest depression. After laughter therapy, serotonin
increased in all three groups (the group without depression,
with a little depression, and with severe depression) except
the control group, and the group with severe depression
showed the greatest change (Cha and Hong 2015).
Serotonin is a control hormone, which controls impulsivity
and tension to maintain calmness and activate the limbic
system, so that it becomes a source of the will to live and
vitality. Therefore, it is a substance that acts in opposition
to depression (Lee 2010). Due to this characteristic, sero-
tonin is drawing people’s attention in its role in healing
anxiety, stress, antisocial behavior, and mental diseases. In
particular, serotonin is known to be activated by continuous
exercise or yoga (Kim 2006). As exercise or yoga increases
the positive energy and vitality of the body and activates
serotonin in the blood, so laughter has a similar inuence to
adequate exercise or yoga by increasing our pulse and lung
capacity and helping the digestive system (Dolgoff-Kaspar
et al. 2012). Therefore, as it increases blood dopamine and
serotonin concentration, laughter therapy may be very
effective in reducing depression as a non-pharmacological,
Laughter therapy as a non-pharmacological, alterna-
tive treatment does not require specialized preparations
such as suitable facilities and equipment, is not prohibited
by cost, does not depend on when or where it happens, and
is easily accessible and acceptable (Mora-Ripoll 2010; Ko
and Youn 2011). For these reasons, the medical world has
taken notice and attempted to include it to more traditional
therapies. Laughter therapy gives our body various physio-
logical changes, and has an inuence on the physical tem-
perature, blood pressure, lung capacity, heart rate, muscles
in the musculoskeletal system, and brain activity, so it can
have an overall effect in promoting health (Hayashi et al.
2007; Bennett and Lengacher 2009). Mentally, laughter
therapy helps reduce unpleasant feelings such as tension,
anxiety, hatred, and anger, alleviates feelings of depression,
aids better interpersonal relationships, and improves insom-
nia, memory failure, and dementia (Takeda et al. 2010;
Bains et al. 2015). As modern society has an issue with the
effect that erce competition and socioeconomic problems
have on quality of life and that stress and depression from
these problems can have a negative inuence on a person’s
mental health, the promotion of mental health through
laughter therapy can be a very effective and meaningful
approach (Bast and Berry 2014). Laughter therapy for
stress and depression, representative cases that have a nega-
tive inuence on mental health, is a noninvasive and non-
pharmacological alternative treatment. Laughter is a posi-
tive sensation, and seems to be a useful and healthy way to
overcome stress. Decreasing stress-making hormones
found in the blood, laughter can mitigate the effects of
stress (Farifteh et al. 2014). There is also an opinion that
laughter is a pleasant stress, which means laughter is a
stress that has a positive aspect and gives fresh and powerful
energy. Thus, laughter is used to reduce negative cognitive
responses and relieves stress (Bennett 2003; MacDonald
2004). Therefore, it is effective and scientically supported
as either a single or adjuvant therapy. At the same time, it
can also provide a comprehensive approach that can
improve the quality of life and social relationships.
This study was supported by Sahmyook University.
Conict of Interest
The author declares no conict of interest.
Apte, M.L. (1985) Humor and laughter: An Anthropological
Approach, Cornell Univercity Press, Ithaca, NY.
Arminen, I. & Halonen, M. (2007) Laughing with and at Patients:
the Roles of Laughter in Confrontations in Addiction Group
Therapy. The Qualitative Report, 12, 484-513.
Ashby, F.G., Isen, A.M. & Turken, A.U. (1999) A neuropsycho-
logical theory of positive affect and its inuence on cognition.
Psychol. Rev., 106, 529-550.
Bains, G.S., Berk, L.S., Lohman, E., Daher, N., Petrofsky, J.,
Schwab, E. & Deshpande, P. (2015) Humors effect on short-
term memory in healthy and diabetic older adults. Altern.
Ther. Health Med., 21, 16-25.
Bast, E.S. & Berry, E.M. (2014) Laugh away the fat? Therapeutic
humor in the control of stress-induced emotional eating.
Rambam Maimonides Med. J., 5, e0007.
Bennett, H.J. (2003) Humor in medicine. South. Med. J., 96,
Bennett, M.P. & Lengacher, C. (2006) Humor and laughter may
inuence health: II. complementary therapies and humor in a
clinical population. Evid. Based Complement. Alternat. Med.,
Bennett, M.P. & Lengacher, C. (2008) Humor and laughter may
influence health: III. laughter and health outcomes. Evid.
Based Complement. Alternat. Med., 5, 37-40.
Bennett, M.P. & Lengacher, C. (2009) Humor and laughter may
inuence health IV. humor and immune function. Evid. Based
Complement. Alternat. Med., 6, 159-164.
Bennett, M.P., Zeller, J.M., Rosenberg, L. & McCann, J. (2003)
The effect of mirthful laughter on stress and natural killer cell
activity. Altern. Ther. Health Med., 9, 38-45.
Berk, L. & Tan, S. (1995) Eustress of mirthful laughter modulates
the immune system lymphokine interferon-gamma. Proceed-
ings of the Society of Behavioral Medicine’s 16th Annual
Scientic Sessions. Ann. Behav. Med. Suppl., 17, C064.
Berk, L.S., Tan, S.A., Fry, W.F., Napier, B.J., Lee, J.W., Hubbard,
R.W., Lewis, J.E. & Eby, W.C. (1989a) Neuroendocrine and
stress hormone changes during mirthful laughter. Am. J. Med.
Sci., 298, 390-396.
Berk, L.S., Tan, S.A., Napier, B.J. & Eby, W.C. (1989b) Eustress
of mirthful laughter modies natural killer cell activity. Clin.
Res., 37, 115A.
Bleuler, E. (1911) Dementia Praecox Oder Gruppe der Schizo-
phrenien, Deuticke, Leipzig, Germany.
Brown, A.S. & Gershon, S. (1993) Dopamine and depression. J.
Neural Transm. Gen. Sect., 91, 75-109.
Caspi, A., Sugden, K., Moffitt, T.E., Taylor, A., Craig, I.W.,
Harrington, H., McClay, J., Mill, J., Martin, J., Braithwaite, A.
& Poulton, R. (2003) Inuence of life stress on depression:
moderation by a polymorphism in the 5-HTT gene. Science,
Cha, M.Y. & Hong, H.S. (2015) Effect and path analysis of
laughter therapy on serotonin, depression and quality of life in
middle-aged women. J. Korean Acad. Nurs., 45, 221-230.
Cho, E.A. & Oh, H.E. (2011) Effects of laughter therapy on
depression, quality of life, resilience and immune responses in
breast cancer survivors. J. Korean Acad. Nurs., 41, 285-293.
Cousins, N. (1976) Anatomy of an illness (as perceived by the
patient). N. Engl. J. Med., 295, 1458-1463.
Cousins, N. (1989) “The Laughter Connection”, Head First: The
Potential Therapeutic Benets of Laughter in Mental Health 249
Biology of Hope and the Healing Power of the Human Spirit,
Penguin Books, New York, NY.
Dean, R.A.K. & Gregory, D.M. (2004) Humor and laughter in
palliative care: an ethnographic investigation. Palliat. Support.
Care, 2, 139-148.
Dolgoff-Kaspar, R., Baldwin, A., Johnson, M.S., Edling, N. &
Sethi, G.K. (2012) Effect of laughter yoga on mood and heart
rate variability in patients awaiting organ transplantation: a
pilot study. Altern. Ther. Health Med., 18, 61-66.
Ekman, P. (1984) Expression and the nature of emotion.
Approaches to Emotion, 3, 19-344.
Ekman, P., Davidson, R.J. & Friesen, W.V. (1990) The Duchenne
smile: emotional expression and brain physiology: II. J. Pers.
Soc. Psychol., 58, 342-353.
Evans, R.G. (1982) Skill versus chance tasks comparison of locus
of control, Ddfensive externality, and persistence. Pers. Soc.
Psychol. Bull., 8, 129-133.
Farifteh, S., Mohammadi-Aria, A., Kiamanesh, A. & Mofid, B.
(2014) The impact of laughter yoga on the stress of cancer
patients before chemotherapy. Iran. J. Cancer Prev., 7,
Freud, S. (1928) On humor. The Psychoanalytic Review (1913-
1957), 15, 85.
Fry, W.F. & Salameh, W.A. (1987) Handbook of Humor and
Psychotherapy: Advances in the Clinical Use of Humor,
Professional Resource Exchange, Inc, Sarasota, FL.
García-Rodera, M. (2007) Cómo beneciarse del poder de la risa,
edited by Morales I, Torres, Madrid, Barcelona.
Gelkopf, M., Gonen, B., Kurs, R., Melamed, Y. & Bleich, A.
(2006) The effect of humorous movies on inpatients with
chronic schizophrenia. J. Nerv. Ment. Dis., 194, 880-883.
Ghodsbin, F., Ahmadi, Z.S., Jahanbin, I. & Sharif, F. (2014) The
effects of laughter therapy on general health of elderly people
referring to jahandidegan community center in Shiraz, Iran,
2014: a randomized controlled trial. Int. J. Community Based
Nurs. Midwifery, 3, 31-38.
Hasan, H. & Hasan, T.F. (2009) Laugh yourself into a healthier
person: a cross cultural analysis of the effects of varying levels
of laughter on health. Int. J. Med. Sci., 6, 200-211.
Hayashi, T., Tsujii, S., Iburi, T., Tamanaha, T., Yamagami, K.,
Ishibashi, R., Hori, M., Sakamoto, S., Ishii, H. & Murakami,
K. (2007) Laughter up-regulates the genes related to NK cell
activity in diabetes. Biomed. Res., 28, 281-285.
Hyeong Woo, P. (2010) The effect of laughter therapy program on
mental health. Korean J. Str. Res., 18, 287-294.
Isen, A.M. & Means, B. (1983) The inuence of positive affect on
decision-making strategy. Soc. Cogn., 2, 18-31.
Ivancevich, J.M. & Matteson, M.T. (1980) Stress and Work: A
Managerial Perspective, Scott, Foresman Dallas.
Keith-Spiegel, P. (1972) Early Conceptions of Humor: Varieties
and Issues, Academic Press, New Uork, NY.
Kim, H. (2006) Effects of 20 weeks yoga on neurotransmitter in
educable mentally retarded teenagers [master’s thesis], Sook-
myung Women’s University, Seoul.
Ko, H.J. & Youn, C.H. (2011) Effects of laughter therapy on
depression, cognition and sleep among the community‐
dwelling elderly. Geriatr. Gerontol. Int., 11, 267-274.
Lazarus, R.S. & Folkman, S. (1984) Coping and Adaptation. The
handbook of Behavioral Medicine, edited by Gentry, W.D.
Guilford, New York, p. 282-325.
Lebowitz, K.R. (2002) The effects of Humor on Cardiopulmonary
Functioning, Psychological Well-Being, and Health Status
among Older Adults with Chronic Obstructive Pulmonary
Disease, The Ohio State University, Columbus, OH.
Lee, S. (2010) Serotonin Here & Now, Joongang Books, Seoul,
Lefcourt, H.M. & Martin, R.A. (2012) Humor and Life Stress:
Antidote to Adversity, Springer Science & Business Media,
New York, NY.
MacDonald, L.C.M. (2004) A chuckle a day keeps the doctor
away: therapeutic humor & laughter. J. Psychosoc. Nurs.
Ment. Health Serv., 42, 18-25.
MacGhee, P.E. & Pistolesi, E. (1979) Humor: Its origin and devel-
opment, W.H. Freeman and Company, San Francisco, CA.
Martin, R.A. (2010) The Psychology of Humor: An Integrative
Approach, Academic Press, Cambridge, Massachusetts.
Martin, R.A. & Lefcourt, H.M. (2004) Sense of humor and phys-
ical health: theoretical issues, recent ndings, and future direc-
tions. Humor, 17, 1-20.
Mora-Ripoll, R. (2010) The therapeutic value of laughter in medi-
cine. Altern. Ther. Health Med., 16, 56-64.
Omwake, L. (1937) A study of sense of humor: its relation to sex,
age, and personal characteristics. J. Appl. Psychol., 21,
Provine, R. (2000) The science of laughter. Psychol. Today, 33,
Ripoll, R.M. & Rodera, M.C.G. (2008) Therapeutical value of
laughter in medicine. Med. Clin. (Barc.), 131, 694-698.
Sahakian, A. & Frishman, W.H. (2007) Humor and the cardiovas-
cular system. Altern. Ther. Health Med., 13, 56-58.
Scholl, J.C. & Ragan, S.L. (2003) The use of humor in promoting
positive provider-patient interactions in a hospital rehabilita-
tion unit. Health Commun., 15, 319-330.
Schultz, T.R. & Horibe, F. (1974) Development of the apprecia-
tion of verbal jokes. Dev. Psychol., 10, 13-20.
Shahidi, M., Mojtahed, A., Modabbernia, A., Mojtahed, M.,
Shafiabady, A., Delavar, A. & Honari, H. (2011) Laughter
yoga versus group exercise program in elderly depressed
women: a randomized controlled trial. Int. J. Geriatr. Psychi-
atry, 26, 322-327.
Sonnentag, S. & Frese, M. (2003) Stress in Organizations, Wiley
Stearns, F.R. (1972) Laughing: Physiology, Pathophysiology,
Psychology, Pathopsychology, and Development, Charles C
Thomas Pub. Ltd., Springeld, IL.
Takeda, M., Hashimoto, R., Kudo, T., Okochi, M., Tagami, S.,
Morihara, T., Sadick, G. & Tanaka, T. (2010) Laughter and
humor as complementary and alternative medicines for
dementia patients. BMC Complement. Altern. Med., 10, 1-7.
Wooten, P. (1996) Humor: an antidote for stress. Holist. Nurs.
Pract., 10, 49-56.
Wortzel, H.S., Oster, T.J., Anderson, C.A. & Arciniegas, D.B.
(2008) Pathological laughing and crying. CNS Drugs, 22,