Le bâillement, du réflexe à la pathologie
Le bâillement : de l'éthologie à la médecine clinique
Le bâillement : phylogenèse, éthologie, nosogénie
 Le bâillement : un comportement universel
La parakinésie brachiale oscitante
Yawning: its cycle, its role
Warum gähnen wir ?
Fetal yawning assessed by 3D and 4D sonography
Le bâillement foetal
Le bâillement, du réflexe à la pathologie
Le bâillement : de l'éthologie à la médecine clinique
Le bâillement : phylogenèse, éthologie, nosogénie
 Le bâillement : un comportement universel
La parakinésie brachiale oscitante
Yawning: its cycle, its role
Warum gähnen wir ?
Fetal yawning assessed by 3D and 4D sonography
Le bâillement foetal

mystery of yawning 














haut de page









mise à jour du
14 avril 2014
Physiology Behavior
A Thermal Window for Yawning in Humans:
Yawning as a Brain Cooling Mechanism
Jorg J. M. Massen, Kim Dusch,
Omar Tonsi Eldakar, Andrew C. Gallup 


Andrew C. Gallup. Yawning and the thermoregulatory hypothesis
The thermoregulatory theory of yawning posits that yawns function to cool the brain in part due to counter-current heat exchange with the deep inhalation of ambient air. Consequently, yawning should be constrained to an optimal thermal zone or range of temperature, i.e., a thermal window, in which we should expect a lower frequency at extreme temperatures. Previous research shows that yawn frequency diminishes as ambient temperatures rise and approach body temperature, but a lower bound to the thermal window has not been demonstrated. To test this, a total of 120 pedestrians were sampled for susceptibly to self-reported yawn contagion during distinct temperature ranges and seasons (winter: 1.4oC, n = 60; summer: 19.4oC, n = 60). As predicted, the proportion of pedestrians reporting yawning was significantly lower during winter than in summer (18.3% vs. 41.7%), with temperature being the only significant predictor of these differences across seasons. The underlying mechanism for yawning in humans, both spontaneous and contagious, appears to be involved in brain thermoregulation.
1. Introduction
Yawning occurs with an average duration of 4 to 7 sec, and consists of three distinct phases: an active gaping of the jaw with inspiration, a brief period of acme corresponding with apnea and peak muscle contraction, and a passive closure of the jaw with shorter expiration [1]. In humans [2], as well as a handful of other social vertebrates [3-7], yawning can be categorized into two basic forms: spontaneous and contagious. Both forms include similar motor action patterns, but spontaneous yawns seem to be triggered by physiological mechanisms of homeostasis and arousal since they reliably occur during distinct behavioral contexts [8, 9] and follow a consistent circadian pattern [10]. In contrast, contagious yawns are elicited simply by sensing or even thinking about the action in others [11]. Unlike its spontaneous form, which appears evolutionarily older by its observed presence in all classes of vertebrates [12] and early onset in uterine development [13], contagious yawning appears to be a more recently derived behavior as evidenced by its presence in relatively few highly social species [2-7] and delayed ontogeny [14-18]. Research investigating contagious yawning has emphasized the influence of interpersonal and emotional-cognitive variables on its expression [4, 5, 19-28], but there have been few attempts to combine theoretical frameworks when explaining both contagious and spontaneous effects. Due to the potential multifunctionality of yawning across species [12,29], however, recent reports on social primates have highlighted potentially important differences in yawn morphology or intensity [5, 30, 31] Although it is commonly believed that yawns serve a respiratory function, experimental procedures have shown yawn frequency is independent of brain/blood levels of O2 and CO2 [32]. A more recent theory, which posits that the motor action of yawning functions as a brain cooling mechanism [33, 34], has received growing empirical support [reviewed by 35]. For example, research on both rats and humans shows that yawning is preceded by intermittent rises in brain temperature and localized mild hyperthermia and then followed by equivalent decreases in temperature immediately thereafter [36, 37]. While various critiques have been proposed regarding the thermoregulatory theory [38-42], no study has found evidence contrary to its main predictions and all current arguments remain untenable [35, 43].
According to the thermoregulatory theory, the cooling effects of yawns occur through thermoregulatory mechanisms of counter-current heat exchange, evaporative cooling and enhanced cerebral blood flow [44]. Consequently, the effectiveness of yawning is dependent on the ambient air temperature, and the expression of this behavior should be constrained to an optimal thermal zone or range of temperature, i.e., a thermal window. In particular, this theory posits that yawns should (1) increase in frequency with initial rises in ambient temperature, as this stimulates thermoregulatory mechanisms to control temperatures within a normal range, (2) decrease as ambient temperatures draw near or exceed body temperature, since taking a deep inhalation of air above one's body temperature would be counter productive, and likewise (3) should diminish when temperatures fall below a certain point, because thermoregulatory cooling responses are no longer necessary and countercurrent heat exchange could result in deviations below optimal thermal homeostasis. Since both spontaneous and contagious yawns are indistinguishable, aside from different triggers, the predictions of the thermal window hypothesis should apply to both forms. Experimental and observational research reports of spontaneous yawning in non-human primates [10, 5], birds [46, 47], and rats [48] have confirmed the first two predictions of this model. Additionally, it was recently discovered that self-reported contagious yawning frequency in humans varies with seasonal climate variation [49].
In particular, two independent groups of pedestrians were sampled in an arid desert climate (Tucson, AZ, USA): the first in summer (37°C) and the other during 'winter' (22°C). Contagious yawning frequency was significantly lower during the hot summer climate (24% vs 45%), with temperature being the only significant factor contributing to this response after controlling for other variables, such as humidity, sleep and time spent outside. Here we tested the lower bound of the thermal window hypothesis by investigating the frequency of self-reported contagious yawning in a climate with a colder winter season (Vienna, Austria). In this case the summer condition provided temperatures equivalent to those in winter months of Tucson, while the winter condition included temperatures at and slightly below freezing.
4. Discussion
Overall, these results show that significantly fewer pedestrians reported contagious yawning during the cold winter (-4 to 7oC), and that, similar to effects observed in an arid desert climate [49], temperature was the only significant predictor of this response when controlling for other variables. As predicted by the thermal window hypothesis, reports of yawning were constrained to an optimal thermal zone or range of ambient temperature (figure 1). Importantly, changes in daylight across the seasons cannot account for these results. First, a particular time frame was chosen for both studies (between 1 and 3 pm) whereby contagious yawning frequencies remain unchanged [53]. Second, the proportion of people that reported yawning in the summer in Vienna, Austria (current study) was comparable to that of the winter in Tucson, Arizona USA [49], whereas there is a large difference in daylight hours between these samples (Summer in Vienna: ± 16h vs. Winter in Tucson: ± 10h). Lastly, an inverse seasonal pattern emerged between the two study locations; i.e., whereas in Tucson there was a high frequency of reported yawning in winter, and a low frequency of reported yawning in summer, in Vienna there was a high frequency of reported yawning in summer, and a low frequency of reported yawning in winter. Thus, it cannot be generalized that people yawn more or less in winter vs. summer, nor with greater or fewer hours of daylight. Instead, the ambient air temperature accompanying the season appears to determine reported yawn frequency. This report adds to accumulating research suggesting that the underlying mechanism for yawning, both spontaneous and contagious, is involved in brain thermoregulation. The thermoregulatory theory provides clear predictions for both the primitive and derived features of this behavior. That is, the thermoregulatory benefits resulting from yawning provide the mechanism by which arousal or state change can be achieved [8, 10], while the spreading of this behavior, i.e., yawn contagion, would therefore coordinate arousal in a group and enhance overall group vigilance [33]. In addition to enhancing the basic understanding of why we yawn, applications from this research include improved treatment and diagnosis of patients with thermoregulatory problems [34, 37, 54, 55].
1. Barbizet J. Yawning. J Neurol Neurosurg Psychiat 1958;21:203-209.
2. Provine RR, Yawning as a stereotyped action pattern and releasing stimulus. Ethology1986;72:109-122.
3. Anderson JR, Myowa-Yamakoshi M, Matsuzawa T. Contagious yawning in chimpanzees. Proc R Soc B 2004:271:S468-S470.
4. Demuru E, Palagi E. In Bonobos Yawn Contagion Is Higher among Kin and Friends. PLoS ONE 2012:7:e49613.
5. Palagi E, Leone A, Mancini G, Ferrari PF. Contagious yawning in gelada baboons as a possible expression of empathy. PNAS 2009;106:19262-19267.
6. Miller ML, Gallup AC, Vogel AR, Vicario SM, Clark AB. Evidence for contagious behaviors in budgerigars (Melopsittacus undulatus): An observational study of yawning and strecthing. Behav Process 2012;89:264-270.
7. Joly-Mascheroni RM, Senju A, Shepherd AJ. Dogs catch human yawns. Biol Lett 2008;4:446-448
8. Baenninger R. On yawning and its functions. Psychon Bull Rev 1997;4:198-207.
9. Deputte BL. Ethological study of yawning in primates. I. Quantitative analysis and study ofcausation in two species of old world monkeys (Cercocebus albigena and Macaca fascicularis). Ethology 1994;98:221-245.
10. Provine, RR, Hamernik, HB, Curchack, BC. Yawning: relation to sleeping and stretching in humans. Ethology 1987;76:152-160.
11. Provine RR. Yawning: the yawn is primal, unstoppable and contagious, revealing the evolutionary and neural basis of empathy and unconscious behavior. Am Sci 2005;93:532-539.
12. Baenninger R. Some comparative aspects of yawning in Betta splendens, Homo sapiens, Panthera leo, and Papio sphinx. J Comp Psychol 1987;101:349-354.
13. de Vries JIP, Visser GHA, Prechtl HF. The emergence of fetal behaviour. I. Qualitative aspects. Early Hum Develop 1982;7:301-322.
14. Anderson JR, Meno P. Psychological influences on yawning in children. Curr Psychol Lett Behav Brain Cog 2003:11;2-7
15. Millen A, Anderson JR. Neither infants nor toddlers catch yawns from their mothers. Biol Lett 2010;7: 440-442.
16. Hoogenhout M, van der Straaten K, Pileggi L-A, Malcolm-Smith S. Young children display contagious yawning when looking at the eyes. J Child Adolesc Behav 2013;1:1.
17. Madsen EA, Persson T. Contagious yawning in domestic dog puppies (Canis lupis familiaris): the effect of ontogeny and emotional closeness on low-level imitation in dogs. Anim Cogn 2012;16: 233&endash;240.
18. Madsen, EA, Persson, T, Sayehli, S, Lenninger, S, Sonesson, G. Chimpanzees show adevelopmental increase in susceptibility to contagious yawning: A test of the effect of ontogeny and emotional closeness on yawn contagion. PLoS ONE 2013;8:e76266.
19. Campbell MW, de Waal FBM. Ingroup-Outgroup Bias in Contagious Yawning by Chimpanzees Supports Link to Empathy. PLoS ONE 2011;6: e18283.
20. Norscia I, Palagi E. Yawn contagion and empathy in Homo sapiens. PLoS ONE 2011;6: e28472.
21. de Waal FBM. Empathy in primates and other mammals. In: Decety J, editor. Empathyfrom bench to bedside, Cambridge: MIT Press; 2012, p. 87-106.
22. Platek SM, Critton SR, Myers TE, Gallup GG. Contagious yawning: the role of selfawareness and mental state attribution. Cogn Brain Res 2003;17:223-227.
23. Platek SM, Mohamed FB, Gallup GG Jr. Contagious yawning and the brain. Cognit BrainRes 2005;23:448&endash;452.
24. Arnott SR, Singhal A, Goodale MA. An investigation of auditory contagious yawning. CognAffect Behav Neurosci 2009;9:335&endash;342.
25. Nahab FB, Hattori N, Saad ZS, Hallett M. Contagious yawning and the frontal lobe: AnfMRI study. Hum Brain Mapp 2009;30:1744&endash;1751.
26. Haker H, Kawohl W, Herwig U, Rossler W. Mirror neuron activity during contagiousyawning &endash; an fMRI study. Brain Imaging Behav 2013;7: 28-34
27. Cooper NR, Puzzo I, Pawley AD, Bowes-Mulligan RA, Kirkpatrick EV, Antoniou PA,Kennett S. Bridging a yawning chasm: EEG investigations into the debate concerning the role of the human mirror neuron system in contagious yawning. Cogn Affect Behav Neurosci 2012;12: 393-405.
28. Massen JJM, Vermunt DA, Sterck EHM. Male yawning is more contagious than femaleyawning among chimpanzees (Pan troglodytes). PLoS ONE 2012;7:e40697.29. Gallup AC. Why do we yawn? Primitive versus derived features. Neurosci Biobehav Rev 2011;35:765-769.
30. Leone, A, Ferrari, PF, Palagi, E. Different yawns, different functions? Testing social hypotheses on spontaneous yawning in Theropithecus gelada. Sci Reports 2014;4.
31. Vick, SJ, Paukner, A. Variation and context of yawns in captive chimpanzees (Pan troglodytes). Am J Primatol 2010;72:262-269.
32. Provine, RR, Tate, BC, Geldmacher, LL. Yawning: No effect of 3&endash;5% CO2, 100% O2, andexercise. Behav Neur Biol 1987;48:382-393.
33. Gallup AC, Gallup Jr GG. Yawning as a brain cooling mechanism: Nasal breathing andforehead cooling diminish the incidence of contagious yawning. Evol Psychol 2007;5:92-101.
34. Gallup AC, Gallup Jr GG. Yawning and thermoregulation. Physiol Behav 2008;95:10-16.
35. Gallup AC, Eldakar OT. The thermoregulatory theory of yawning: what we know from fiveyears of research. Front Neurosci 2013;6:1-13.
36. Shoup-Knox ML, Gallup AC, Gallup Jr GG, McNay EC. Yawning and stretching predictbrain temperature changes in rats: support for the thermoregulatory hypothesis. Front Evol Neurosci 2010;2:1-5.
37. Gallup GG Jr, Gallup AC. Excessive yawning and thermoregulation: two case studies of chronic, debilitating bouts of yawning. Sleep Breath 2010;14:157-159.
38. Walusinski O. Why do we yawn? Past and current hypotheses. In: Shoja MM, Agutter PS, Tubbs RS, Ghanei M, Ghabili K, Harris A, Loukas M, editors. Hypotheses in Clinical Medicine, Hauppauge, NY;Nova Science Publishers: 2013, p. 245-256.
39. Elo H. Yawning and thermoregulation. Sleep Breath 2010;14:391-392.
40. Elo H. Yawning cannot cause significant temperature decreases in humans. Sleep Med. 2011;12:102.
41. Guggisberg AG, Mathis J, Schnider A, Hess CW. Why do we yawn? Neurosci Biobehav Rev 2010;34:1267-1276.
42. Guggisberg AG, Mathis J, Schnider A, Hess C W. Why do we yawn? The importance of evidence for specific yawn-induced effects. Neurosci Biobehav Rev 2011;35:1302-1304.
43. Gallup AC. The thermoregulatory hypothesis of yawning: time to reconsider terms such as "impossible" and "cannot" and evaluate theories based on evidence. Sleep Med 2011;12:102-103.
44. Gallup AC, Hack GD. Human paranasal sinuses and selective brain cooling: A ventilation system activated by yawning? Med Hypotheses 2011;77:970-973
45. Campos FA, Fedigan LM. Behavioural adaptations to heat stress and water scarcity in white-faced capuchins (Cebus capucinus) in Santa Rosa National Park, Costa Rica. Am J Phys Anthropol 2009;138:101-111.
46. Gallup AC, Miller ML, Clark AB. Yawning and thermoregulation in budgerigars(Melopsittacus undulatus). Anim Behav 2009;77:109-113.
47. Gallup AC, Miller ML, Clark AB. The direction and range of ambient temperature influencesyawning in budgerigars (Melopsittacus undulatus). J Comp Psychol 2010;124:133-138.
48. Gallup AC, Miller RR, Clark AB. Changes in ambient temperature trigger yawning but notstretching in rats. Ethology 2011;117:145-153.
49. Gallup AC, Eldakar OT. Contagious yawning and seasonal climate variation. Front Evol Neurosci 2011;3(3):1-5.
50. Greco M, Baenninger R. Self-report as a valid measure of yawning in the laboratory. Bull Psychonomic Soc 1989;27:75-76.
51. Giganti F, Toselli M, Ramat S. Developmental trends in a social behaviour: contagiousyawning in the elderly. Eta Evolutiva 2012;34:111-117.
52. Baenninger R, Greco M. Some Antecedents and Consequences of Yawning. Psychol Rec1991;41:453-460.
53. Giganti F, Zilli I. The daily time course of contagious and spontaneous yawning among humans. J Ethol 2011;29:215-219.
54. Gallup AC, Gallup GG Jr, Feo C. Yawning, sleep, and symptom relief in patients withmultiple sclerosis. Sleep Med 2010;11:329&endash;330.
55. Gallup AC, Gallup JA. Frequent yawning as an initial signal of fever relief. Med Hypotheses2013;81:1034-1035.