Yawn

A yawn is a reflex characterized by a long inspiratory phase with gradual mouth gaping, followed by a brief climax with muscle stretching, and a rapid expiratory phase with... Wikipedia

• Organisms:  Vertebrates
• Biological system:  Nervous system
• Health:  Unaffected or beneficial
• Action:  Involuntary
• Stimuli:  Fatigue, Boredom, Stress, Sleepiness, Others mirror neuron reflex
• Method:  Complete extension of jaw, inhalation, eyes close, stretching of the eardrum, exhalation
• Duration:  Usually 6 seconds
• Data source:  DuckDuckGo