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Updated: Jun 14, 2026

A Laboratory Method to Measure Contagious Yawning in Rats
Published on: June 14, 2019
Interplay between yawning and vigilance: a review of the experimental evidence
Background:
Yawning is a phylogenetically old behavior of ubiquitous occurrence. The origin and function of this conspicuous phenomenon have been subject to speculation for centuries. A widely held hypothesis posits that yawning increases the arousal level during sleepiness; thus, providing a homeostatic regulation of vigilance.
Methods:
This chapter reviews experimental data on the relationship between yawning and vigilance that allow testing of the components and predictions of this hypothesis.
Results:
Behavioral studies and electroencephalographic (EEG) recordings of brain activity before and after yawning have provided consistent evidence that yawning occurs during states of low vigilance; thus, substantiating the notion that it is provoked by sleepiness. However, studies analyzing autonomic nervous activity and EEG-based indices of vigilance in yawning subjects did not find specific autonomic activations or increased arousal levels after yawning.
Conclusions:
The data therefore do not support an arousing effect of yawning or a role in regulation of vigilance or autonomic tone.
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