Emotional tears include larger quantities of stress hormones than basal (also known as lubricating) or reflex tears, according to studies of the various types of tears (the ones that form when you get something in your eye). Emotional tears also include more manganese, which regulates mood, than other kinds. Other elements found in higher amounts in emotional tears include zinc and calcium. Basal tears are thought to play a role in maintaining the surface of the eye clean and clear of irritants and bacteria. They are usually dry enough to wipe away with a tissue. Reflex tears are quickly produced upon stimulation of any nerve ending distributed within the lacrimal gland, such as when brushing against something sharp. These are the kind of tears that will suddenly flow when you wake up one morning and find that you cannot open your eye properly because there is something in it. These are also the kind of tears that cry witnesses to crime scenes around the world. Stress hormones increase blood flow to certain areas of the body, including the face, causing the eyes to flush and tear. This helps us release negative feelings so they don't build up inside of us. Stress can also cause the lacrimal glands under the skin of the upper eyelid to produce more fluid, which then drains down into the tear film. The brain senses this change in fluid level and triggers the release of additional tears. People who suffer from depression often report that their eyes feel dry.