Psychogenic lacrimation is the term that describes tearing up or crying as an emotional response. This type of tears is typically associated with anger, sadness, or even extreme happiness or relief. But what is the underlying reason that we tear up when we are sad?
To answer that, let’s first examine how our tears are made. The bulk of our tears is produced by the lacrimal glands. We have one of these glands in each eye, and they sit just under the temporal (outer) aspect of our upper eyelids. There are three main types of tears that these glands produce.
The first tears we will discuss are the basal tears. These are the "baseline" tears which always cover the front surface of our eyes. If your eyes are normal and healthy, these basal tears are coating the surface of your eyes right now, creating a "tear lens" which helps keep your vision clear. In certain conditions like dry eye syndrome, there is a lack of these basal tears.
The second tear category is the reflex tears. These tears, as you might have guessed, are created in response to some (usually) external stimulus.
An eyelash or a piece of dust that blows into your eye causes the lacrimal glands to ramp up tear production in an effort to flush the foreign matter from your eye. In the case of dry eye syndrome, the front surface of the eye becomes dried out. This dry feeling creates the same reflex, as the body tries to re-lubricate the surface of the eye quickly. These reflex tears, however, do not have the same properties as the basal tears, and are made not to stay in the eye. The job of the reflex tears is to run out of the eye and down the face. Thus, many people who have dry eye syndrome actually report that their eyes are "watery." Many times when I've told patients they have dry eyes, I have heard, "no doc, I have WET eyes!" The tearing of the eyes in these cases is due to reduction in the normal basal tears and an overcompensation of the lacrimal glands, producing reflex tears.
Which brings us to the third tear category: Psychogenic lacrimation, also known as emotion tears or psychic tears. This is the least understood of the tear categories. Some studies have shown that psychogenic tears contain more toxins than reflex tears, and there are theories which contend that these tears help shed toxins and other unwanted substances from the body. Others believe that psychogenic lacrimation is a recovery from the "fight or flight" stage of emotional stress. When a stressor is introduced, our sympathetic nervous system kicks in: our pupils dilate, our bladders tighten, our muscles constrict-- evolutionary traits which ready the body to escape or fight off impending danger. Once the danger has passed, our bodies relax, and the other side of our nervous system (the parasympathetic) kicks in. Pupils constrict, muscles relax. Sometimes, we cry. Lacrimation is also stimulated by the parasympathetic nervous system. This is why a lost child may not cry when he first notices he's suddenly alone in the supermarket, but may cry once he comes across the parents again. You may notice the same delay when a child falls and hurts herself: she may stand up, brush herself off, and only cry as you're running over to make sure she's okay. Some psychologists also believe psychogenic lacrimation is a signal to others that we need help, a survival mechanism to let others know you are in distress. Most likely, the true cause of this type of tearing comes from a combination of all these theories.
Whatever the cause, it seems a good cry might be therapeutic. It may help by releasing toxins, it may function as a part of stress relief, allowing the body to recover, or may simply be a signal to our friends and family that we need them. So whether it's a wedding or a funeral, go ahead and open the floodgates. It might just be good for you.