Tears are a natural bodily fluid, continuously produced to maintain eye health and function. They lubricate the ocular surface, ensuring smooth eyelid movement and clear vision. Tears also protect by washing away dust, debris, and irritants. This constant production and flow are fundamental to eye comfort and defense.
The Composition and Types of Tears
The eye produces three distinct types of tears, each with a specific function. Basal tears are present constantly, forming a thin film over the eye to keep it lubricated and nourished. Reflex tears are generated in response to irritants like smoke, dust, or onion fumes, acting to flush out foreign substances. Emotional tears, conversely, are shed during strong emotional experiences, whether sadness, joy, or stress.
Tears are primarily composed of water, but they also contain electrolytes, proteins, lipids, and mucins, which together form a complex, multi-layered film. The outermost lipid layer, produced by meibomian glands, helps prevent evaporation. The middle aqueous layer, the thickest, provides hydration and contains salts, antibodies, and enzymes like lysozyme that fight bacteria. The innermost mucin layer helps the tear film spread evenly and adhere to the eye’s surface.
While basal and reflex tears share a similar basic composition, emotional tears have been found to contain higher concentrations of certain stress hormones, such as adrenocorticotropic hormone and prolactin, as well as natural painkillers like leucine enkephalin. These chemical differences suggest a biological role for emotional crying beyond mere lubrication or irritation removal.
Understanding the “Hot” Sensation
Tears, when they emerge from the eyes, are at body temperature, approximately 98.6°F (37°C). The sensation of “hotness” often perceived when crying is not due to superheated tears, but rather results from several physiological factors. One contributing element is temperature contrast; the skin around the eyes and on the face may be slightly cooler than the tears, causing the body-temperature fluid to feel warm by comparison as it streams down the cheek.
Evaporation also plays a role in this perception. While evaporation typically leads to a cooling effect, the initial spreading of the tear film across the skin can create a momentary sensation of warmth before the cooling process begins.
During intense emotional states, there is often increased blood flow, or vasodilation, to the face. This rise in local skin temperature can make the tears, already at body temperature, feel even warmer against the flushed skin. The brain’s interpretation of sensory signals from nerve endings in the skin also contributes to this subjective feeling of heat.
The Role of Emotions in Tear Characteristics
Strong emotions influence the overall experience of crying, thereby contributing to the perceived “hot” sensation of tears. During intense emotional crying, the autonomic nervous system, particularly its sympathetic branch, becomes highly active. This sympathetic activation triggers several physiological changes throughout the body.
Such changes include an increased heart rate and heightened muscle tension. This activation also leads to vasodilation, an expansion of blood vessels, in the facial area. This increased blood flow raises the local skin temperature of the face, creating a generalized feeling of warmth. When body-temperature tears then flow over this warmer facial skin, the sensation of heat is amplified, making the tears feel distinctly hotter. The intensity of the emotional state can directly correlate with the degree of this physiological response and, consequently, the perceived warmth of the tears.