Why do tears come out when we cry

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Last updated: April 8, 2026

Quick Answer: Tears emerge during crying primarily due to emotional triggers that activate the lacrimal system, producing about 1.1 milliliters of tears per minute during intense crying episodes. This process involves the lacrimal glands, which secrete tears containing water, electrolytes, proteins like lysozyme, and lipids. Tears then drain through the nasolacrimal ducts into the nasal cavity, explaining why crying often leads to a runny nose. Emotional crying is unique to humans and serves social and physiological functions, such as stress relief through the release of hormones like adrenocorticotropic hormone.

Key Facts

Humans produce three types of tears: basal (0.75 to 1.1 mL per day), reflex (in response to irritants), and emotional (triggered by feelings).
The lacrimal glands, located above each eye, are responsible for tear production and can secrete up to 30 mL of tears per hour during crying.
Tears contain lysozyme, an enzyme that kills bacteria, helping protect the eyes from infections.
Emotional crying releases stress hormones like cortisol and endorphins, which can reduce pain and improve mood.
The nasolacrimal ducts drain tears from the eyes into the nasal cavity, causing a runny nose during crying.

Overview

Tears are a complex biological fluid produced by the lacrimal system, essential for eye health and emotional expression. Historically, tears have been studied since ancient times, with Hippocrates (c. 460–370 BCE) noting their role in health, and Charles Darwin (1872) exploring emotional crying in "The Expression of the Emotions in Man and Animals." In the 20th century, research advanced with the discovery of tear components like lysozyme by Alexander Fleming in 1922. Today, tears are classified into three types: basal tears (continuously lubricating the eyes), reflex tears (from irritants like onions), and emotional tears (linked to feelings). Emotional crying is unique to humans and may have evolved around 200,000 years ago with Homo sapiens, serving social bonding and stress relief functions. Studies show that 85% of women and 73% of men report feeling better after crying, highlighting its psychological impact.

How It Works

The process of tear production during crying involves both neural and physiological mechanisms. When emotional stimuli (e.g., sadness or joy) activate the limbic system in the brain, signals are sent via the autonomic nervous system to the lacrimal glands. These glands, located above each outer eye, secrete emotional tears composed of water, electrolytes (like sodium and potassium), proteins (including lysozyme for antibacterial action), lipids, and hormones such as adrenocorticotropic hormone (ACTH). Tears flow across the eye surface, lubricating and protecting it, then drain through tiny openings called puncta into the nasolacrimal ducts, which channel them into the nasal cavity. This drainage explains the runny nose effect during crying. Reflex tears, triggered by irritants, follow a similar pathway but involve different neural pathways, such as the trigeminal nerve. The entire process is regulated by neurotransmitters like acetylcholine and norepinephrine, ensuring rapid tear production in response to emotional or physical stimuli.

Why It Matters

Understanding why tears come out when we cry has significant real-world implications. Physiologically, tears protect eye health by removing debris, preventing infections with antibacterial components, and maintaining moisture—critical for preventing conditions like dry eye syndrome, which affects about 16 million Americans. Psychologically, emotional crying serves as a coping mechanism, reducing stress by releasing cortisol and endorphins, potentially lowering blood pressure and improving mood. Socially, tears facilitate communication and empathy, strengthening bonds in relationships; for instance, studies show that seeing someone cry can increase prosocial behavior by up to 30%. In medicine, tear analysis is emerging as a non-invasive diagnostic tool for diseases like diabetes and cancer, as tears contain biomarkers reflective of systemic health. Overall, crying is a vital human function with benefits spanning health, psychology, and social interaction.