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mise à jour du 13 mars 2002
 The Psychological Record
 cas cliniques
On the context of yawning:when, where, and why?
Monica Greco Ronald Baenninger
Department of Psychology, Temple University, Philadelphia
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Yawning scale. Questionnaire estimant les bâillements. PDF 


Yawning is a very obvious act in humans and other animals, yet it has not received much attention in either science or daily life. In a recent review of "evolution and facial action in reflex, social motive and paralanguage" yawning received no mention (Fridlund, 1991). To some extent, this lack of interest may be because yawning is rarely life-threatening; in fact, frequent or excessive yawning does accompany a wide range of pathological conditions, including frontal lobe tumors, epidemic encephalitis, supranuclear palsy, certain gastric diseases, brain stem lesions, some forms of epilepsy, motion sickness, narcotic withdrawal, and chorea (Barbizet, 1958; Comroe, 1974; Graybiel & Knepton, 1976; Heusner, 1946; O'Brien, 1976; Rudolph, Barnett, & Einhorn, 1977).

Yawning has been observed in individuals belonging to all classes of vertebrates (Baenninger, 1987; Craemer, 1924) and is one of the very earliest acts that human infants perform (Blanton, 1917). It has been observed in rat fetuses at 20 days (Smotherman & Robinson, 1987). In 1955 Ferrari, Floris, and Paulesu discovered that a yawning-stretching syndrome was elicited in laboratory dogs 30 min after intracerebroventricular injection of ACTH. Subsequent research on pharmacological induction of yawning has suggested that yawning elicitation results from an interaction between inhibitory dopaminergic and excitatory cholinergic influences on a specific motor program, possibly in the brain stem (Urba-Holmgren et al., 1990).

Androgenic influences on yawning have been found. Goy and Resko (1972) showed that testosterone injections produce both yawning and penile erections in male rhesus monkeys; Phoenix and Chambers (1982) found that testosterone propionate, but not estradiol, produced yawning in females and pseudohermaphrodites, as well as in males. In nonhuman primates males yawn significantly more than females; this is not true in humans (Schino & Aureli, 1989). Yawning thus appears widespread phylogenetically, very early ontogenetically, and is subject to a variety of peptide and steroid influences. All of this suggests that it must be an important act, but its functions in our species have remained elusive.

One approach to inferring the functions of a behavioral act is to determine the context in which it occurs, including its antecedents and consequences (Baenninger & Greco, 1991). One of the practical difficulties in studying low-frequency behavioral acts such as yawning is that observers must be very patient; long periods of time may elapse between performances of the act by an individual. Observing groups of people in different situations gives some information; for example, Baenninger (1987) reported data on rates of yawning in lecture classes, subway cars, cafeterias, and so forth. But information on antecedents and consequences of yawning for individuals is not available in such a procedure.

Asking individuals to keep tallies of their own yawning is one approach to solving this problem. Despite our initial reservations about the subjective nature of such personal data, the procedure has been shown to be a valid measure in the laboratory, at least for short time periods (Greco & Baenninger, 1989). Keeping a log specifically for any behavioral act may artificially increase the frequency with which that act is reported, because the attention of log-keepers is more than usually focused on the act. At present we can offer no solution for this potential artifact. In the first part of this report we present data from "yawn logs" kept by volunteer subjects over the course of 1 week.

Another solution to the problem of gathering data is to survey individuals about when they yawn. Whether respondents can report accurately the situations and times of day at which they actually do yawn is, of course, an empirical question. In such a survey, people may report when they think their yawning occurs, but the data may reflect beliefs and common sense" rather than actual fact. In the second part of this report we present results of a survey of yawning that we carried out. By comparing such survey data with personal logs kept by individuals we may reach more valid conclusions about the circumstances under which yawning occurs.


Although there were areas of agreement between the two studies some discrepancies emerged that may reflect differences between keeping a log and responding to a survey: The former represents what subjects actually do, and the latter represents what they believe they do. For example, the log data indicated no relationship between sleep duration and yawning frequency during the following day; survey results indicated that respondents believe that there is a relationship.

Survey respondents believed that they yawn more in the afternoon than in either the morning or evening, but the log results flatly contradict this belief because afternoon hours were when the percentages of daily yawns fell to their lowest levels. Survey respondents believed that lying in bed at night and arising in the morning were both situations where yawning was frequent. Partly supporting this finding, the logs in Study 1 showed that the first hour after waking and the last hour before bed were the times when most yawns occurred, although the logs indicated that it is the activities that accompany retiring to bed and arising in the morning that are associated with yawning. In any event, this temporal variation supports findings of Provine, Hamernik, and Curchak (1987) in humans and of Anias, Holmgren, Urba-Holmgren, and Eguibar (1984) in rats. In rats of a strain selectively bred for a high frequency of yawning (Urba-Holmgren et al., 1990) a clear circadian variation of yawns existed, with a peak frequency in late light and early dark hours (Anias et al., 1984).

Frequent yawning thus appeared to be associated with the transition between different levels of arousal; the log data on actual yawning show that the first hour and the last hour of the waking day are the peaks of yawning frequency. Except for these peaks, mornings and evenings were not periods during which yawning frequency was unusually high however. Relatively few yawns are actually performed during the afternoon, a period when adults do not normally shift from activity to inactivity or vice versa. Apparently the yawns that were emitted in the early and late afternoon were primarily associated with driving.

If yawning is somehow related to level of arousal (Askenasy, 1989; Greco & Baenninger, 1991) one would expect yawns to occur frequently when transitions between different levels of arousal are required, as when people are first getting up in the morning, when they are retiring for the night. A less obvious prediction from this arousal hypothesis is that people should yawn frequently while attending lectures, and when driving a car (both activities in which keen attention and easy relaxation are likely to alternate). This was what we found.

For experienced drivers driving is a relaxed activity for which a certain level of arousal (or at least attention) is needed occasionally. Our log data indicated that driving a car late at night was associated with yawning; survey respondents agreed, and also believed that they were unlikely to yawn while driving on a sunny day with no traffic, or while sitting in traffic. The driving conditions under which logs showed yawning were unfortunately not specified exactly; the majority were commuting to school, but whether they were mainly at speed or stopped in traff ic could not be determined.

Like driving, listening to lectures is an activity in which arousal levels may frequently shift between alert attention and a relaxed state that may border on sleeping. In both studies listening to lectures was the most frequent situation associated with yawning. Over 21% of the yawns were reported in the logs during this activity; informally, college students reported to us that they spend about 3 hr (18% of the day) in lecture classes. Survey respondents overwhelmingly (75%) believed that they were likely to yawn during lectures. This result agrees with an earlier finding that the rate of yawning was higher during lecture classes than while eating, talking, watching TV, riding in the subway, or virtually any other activity observed (Baenninger, 1987). The belief by survey respondents that they yawn most frequently in lectures appears to be correct.

Data on yawning of other vertebrate species have rarely been reported systematically (Baenninger, 1987), but the few studies where yawning has been mentioned support the hypothesis that transitions in arousal level may be associated with frequent yawning. Myrberg (1972) found that damselfish Eupomacentrus partitus yawned when making transitions between various social behaviors such as agonistic responses and nest entrances/exits, a finding confirmed by Baenninger (Il 987) in Siamese fighting fish, Betta spiendens. Among members of the Felidae (Baenninger, 1987), Canidae (Bekoff, 1974), and nonhuman primates (Baenninger, 1987; Hall, 1962; Hinde & Rowell, 1962), transitions between behavioral states (such as anticipation of feeding or play) also appear to be accompanied by yawns. In laboratory rats Holmgren et al. (1991) have reported a food-anticipatory yawning rythmn.

Survey respondents reported that they were likely to yawn when tired or sleep-deprived. Our data from the yawning logs did not support this belief; the lack of any correlation between yawn frequency and hours of sleep during the previous night suggests that this widely held belief is incorrect, at least for our college student subjects (whose sleeping patterns may not be typical of the general population).

Performance of activities that were observed or judged by others was believed by the survey respondents to make yawning unlikely (e.g., being interviewed, giving a speech, or waiting for a competition to begin). The subjects who kept logs did not report any of these public or competitive activities, so we cannot make any clear comparisons. In a general way the log data do confirm these survey results, because relatively few yawns occurred while the log-keepers were working and talking.

Unless they actually keep track of the circumstances under which they yawn, most people probably are not normally aware of their own yawns and are unlikely to recall much about them. When asked, as in our survey, to recall anything about their own yawning they are likely to rely on widely held beliefs or "common sense" rather than on empirical observations of themselves. These beliefs may bear only a marginal relationship to the actual distribution of yawning frequency assessed by keeping logs. This suggests that people may not normally pay much attention to yawning; like breathing, blinking, sighing, and other biologically important acts, yawning is taken for granted and ignored unless it is disrupted or abnormal in some way. Until fairly recently, this lack of attention has also characterized scientific interest in yawning.

voir aussi

Baenninger R, Binkley S, Baenninger M Field observations of yawning and activity in humans.
Baenninger R On yawning and its functions
Baenninger R, Greco M Some antecedents and consequences of yawning
Greco M, Baenninger R On the context of yawning: when, where, and why ?
Baenninger R Some comparative aspects of yawning in Betta sleepnes, Homo Sapiens, Pantera leo and Papio sphinx
Greco M , Baenninger R Effects of yawning and related actvities on skin conductance and heart rate
Is yawning an arousal defense reflex ? Askenasy JJ