Yawning often brings with it a watering of the eyes. While the primary purpose of yawning remains a subject of ongoing scientific inquiry, the accompanying tear production is a more readily understood mechanical response.
The Science of a Yawn
A yawn begins with a deep, prolonged inhalation, often accompanied by a wide opening of the mouth. This is followed by a brief pause and then a slow exhalation. The act involves a coordinated stretching of the jaw, throat, and facial muscles, including those surrounding the eyes. While the exact biological purpose of yawning is not fully established, prevailing theories suggest it may play a role in regulating brain temperature or promoting alertness. Regardless of its primary function, the physical actions involved in yawning exert temporary pressures on the structures within the head and face.
Your Tear System Explained
The human eye possesses a sophisticated system for producing and draining tears. Tears are a complex mixture of water, oils, and mucus, serving multiple roles in maintaining eye health. These fluids lubricate the eye’s surface and act as a protective barrier, washing away dust, debris, and irritants that might enter the eye. The main tear-producing organs are the lacrimal glands, located above the outer corner of each eye. After tears have served their purpose, they drain from the eye through small openings called puncta, found in the inner corner of both the upper and lower eyelids. These puncta lead into tiny tubes, known as canaliculi, which then connect to the nasolacrimal duct, commonly referred to as the tear duct, ultimately emptying into the nasal cavity.
The Link Between Yawning and Tears
The physical mechanics of a yawn directly influence the tear system, explaining why eyes often water during this action. When a person yawns, the intense stretching of facial muscles, particularly those around the eyes and jaw, can exert pressure on the lacrimal glands, causing them to release a small, additional amount of tears. Simultaneously, the same muscle contractions and facial movements can briefly compress the nasolacrimal ducts, which are responsible for draining tears away from the eye. This temporary constriction hinders the normal outflow of tears. The combination of increased tear production from the lacrimal glands and the impeded drainage through the compressed ducts leads to a temporary overflow of tears onto the eye’s surface and sometimes down the cheeks. This physiological response is a normal and harmless consequence of the mechanical forces at play during a yawn.