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 mise à jour du
24 février 2002
Sleep research
1992; 21; 101
Le bâillement, du réflexe à la pathologie
 Yawning elicited by reading: effect of sleepiness
 Mary A Carskadon
Sleep Revearch Laborarory, EP Bradley Hospital
Brown University, Providence, RI
 Carskadon MM Yawning elicited by reading : is an open mouth sufficient stimulus ?
 Is yawning an arousal defense reflex ? Askenasy JJ
 Yawning: an evolutionary perspective Smith EO


Reading about yawning can elicit yawns and is a more effective stimulus than reading a control passage. We wished to examine whether yawning is elicited more easily in students who report greater levels of sleepiness.

Methods : While seated in a large auditorium, students enrolled in a course on sleep and dreaming but naive to inforrnation on yawning were ask-ed to complete the Stanford Sleepiness Scale (SSS) and then were given one of two brief passages to read, with instructions to "remain absolutely quiet and do not look around the room" while reading. A 5 minute reading period was provided. Students were instructed to re-read the passage if they finished early. One passage ("Yawn") described yawning and was the passage previously used by Provine; the second ("Open Wide") was of equal length, but described tonsils and tonsillitis in the context of explaining why a doctor says "open wide and say ah". Students were then requested to report whether thev yawned, were tempted to yawn, did not yawn, or could not remember having yawned while reading the text. They also rated their interest level in the reading (5-point scale-very uninteresting to very interesting), stated how much they had slept the night before, indicated whether they felt the previous night's sleep was sufficient (3-point scale-more than suificient, sufficient, less than sufficient), and finally gave another SSS rating. Responses were completed by 130 students, ranging in age from 16 to 22 (mean = 19.3, S.D. = 1.3) years. The Yawn text was read by 32 women and 31 men and the Open Wide text by 40 women and 27 men. No sex differences were found for any variable; therefore, the data were combined across sexes.

Results : Of the 63 students who read the Yawn passage, 20 reported yawning and 29 having been tempted to yawn; among the 67 who read the Open Wide passage, 4 reported yawning and 17 being tempted to yawn (chi-square = 32. f-3 3; p<001). The level of interest was significantly related to reports of yawning only in the group who read the Open Wide passage; thus, those who found the passage less interesting were more likely to report yawning or being tempted to yawn (chi-square = 10.77; p<01). Figure shows that SSS ratings given before reading either passage did not have a statistically significant effect on reports of yawning; however, SSS ratings given after reading either passage showed a significant relationship to yawning. Furthermore, reported sleep time the night before the experiment was significanny related to the likelihood of yawning; those who reported yawning also reported having had less sleep. Finally only in the group who read the Yawn passage, ratings of sleep sufficiency the night before showed that when sleep was rated as insufficient, students were significantly more likely to report yawning or being tempted to yawn, than those who rated sleep as sufficient or more than sufficient (chi-square = 6.68; df = 1; p<01).

Discussion : Although our previous study showed no relationship between sleep the night before and likelihood of yawning such a relationship occurred in the present study. In addition, a subjective sense of sleepiness measured by the SSS ratina given after reading the text was also associated with likelihood of yawning or being tempted to yawn, even though SSS rated before reading the text was not. At the same time, subjects reading the more potent yawn-eliciting text were more likely to yawn if they rated sleep as insufficient. We suggest that individuals with a high physiological sleep tendency (not measured directly in this study) are more likely to yawn when exposed to a yawn-inducing situation, as indicated by the association of yawning with low sleep times and ratings of insufficient sleep. The yawn-eliciting text may "unmask" a high level of physiological sleepiness that was not apparent on the initial SSS ratings. We further suggest that the occurrence of yawning may itself serve as a cue for introspective ratings, as marked by the closer relationship between yawning or being tempted to yawn and SSS ratings given after than those given before reading the text. On the other hand, the students who yawned may have simply decided they must be sleepier than they first thought.