The act of scratching results in an increase in the flow of blood to the area, while also releasing serotonin, which subsequently eases the muscles being physically stimulated.
We’ve all spent days glaring into our computer screens with stiff backs, holding awkward positions without even realizing it. Unconsciously, we move our fingers over our backs in motions similar to that of scratching. In no time at all, our eyes are closed and we’re scratching our backs, experiencing what we might call a ‘temporary paradise.’ This feeling makes us feel so relieved that it is a legitimate struggle to turn back to the spreadsheet on the screen.
Have you ever realized how that tiny little scratching action, even devoid of an itch, causes you to feel much better than you did 60 seconds ago? Before you unknowingly started scratching your back?
Why do we scratch?
Scratching is nothing but a defense mechanism to get irritants off our skin. The atmosphere that we exist in consists of a lot of suspended particulate matter that can settle on our skin and cause irritation. The dermal cells in our skin are also flanked with sensory receptors called nociceptors, which are sensory neurons that respond to pain.
Scratching is a contagious action, like yawning. Studies have shown that people do tend to scratch themselves upon seeing others doing so. You might even feel itchy and scratch yourself even as you’re reading this article.
Scratching is a reflexive action that is carried out numerous times in a day, whether or not we realize it.
What happens when we scratch our skin?
Whenever irritation or uneasiness occurs on the skin, mast cells are recruited to that area. Mast cells are immune cells that release Histamine, which involved in bringing about inflammatory responses. The action of histamine causes the dilation of blood vessels, in turn causing an increased flow of blood at the site of action.
All these changes are sensed and taken up by the nociceptors. These impulses are carried to the spinal cord. The spinothalamic tract carries these impulses to the brain, which is how the brain learns about the itch. It then commands the motor neurons to bring about the scratching action to quench that irritating little itch.
The physical action of scratching is a pain-inducing one. While scratching, our fingernails cause pain to our skin that is below our pain threshold, so it doesn’t hurt. The mild pain acts as a temporary distraction to the irritated area of our skin. These pain impulses are sent to the spinal cord and eventually to the brain. The brain then releases the neurotransmitter serotonin in order to cope with this mild pain.
Serotonin is often regarded as the ‘happy hormone’, as it imparts a positive feeling. Of all the many functions performed by serotonin, ‘mood regulation’ is a major one. The whole act of scratching leads to an increase in serotonin levels in our bodies. Higher levels of serotonin lead to a more positive state of mind. This is what leaves us feeling satisfied after scratching our skin. The elevated feeling makes us feel so good that we want to continue scratching, so that more serotonin can be secreted by the brain. Thus, the feeling of contentment is what leads to us wanting to scratch the itch even more.
Activation of the Reward System:
The release of the neurotransmitter serotonin is just the trailer to a much longer movie. Recent studies have shown that non-pathological scratching is known to activate the reward system. This Reward System is a pathway activated by positive stimuli. The actions of this pathway impart a positive feeling. The consumption of palatable food and listening to your favorite music are just a few stimuli to name.
It has been observed that the act of scratching not only diminishes an itch, but can be both rewarding and addictive. The itch-scratch cycle is a complex process involving sensory, motor, and emotional components. In turn, it is known to bring about a pleasurable feeling.
Studies carried out on human subjects showed that scratching activated the Ventral Tegmental Area (VTA), substantia nigra (SN), raphe nucleus, and periaqueductal gray (PAG). The Ventral Tegmental Area (VTA) and substantia nigra (SN) are the prime components of the reward system. The periaqueductal gray (PAG) is an anatomical and functional structure present between the forebrain and the lower brainstem that plays a major role in pain modulation.
The Raphae Nucleus is a cluster of nuclei (cluster of neurons) found in the brainstem that produces serotonin. This supports why serotonin is released through scratching. All the above-mentioned areas in the brain are seen to light up during the act of scratching. Since these areas are strongly correlated with pleasurability ratings, scratching is known to impart a feeling of being satisfied.
The magical effect of scratching your back:
At some point in time, we have all come across fancy advertisements for Back Scratchers. It will often portray people seeking immediate relief by using these. As soothing as the thought seems, the science behind instant back relief is interesting.
Modernization has led us into a very sedentary way of life, which means we have to deal with new problems. Day by day, our way of life is getting more stressful. These stressors unknowingly have an effect on our bodies. Of the many parts of our bodies that are an easy target for stress, the back is a major one.
Stress, in various ways, has different effects on our back muscles. The most common effect is the constriction of blood vessels, which limits blood flow. This leads to tension and stiffness in our muscles. Also, a lack of physical exercise or sitting in your chair for long periods of time can cause stiffness and muscle spasms. Thus, we can imagine that after a long day at work, our backs become deep reservoirs of tension.
At this point, when we scratch our backs, even without an irritant, it leads to a whole cascade of reactions. Of all the actions, the most fruitful are the increased blood flow and the release of serotonin. Scratching leads to an increase of blood flow to our back muscles, which were under tension for the majority of the day. Increased circulation eases the tension. The mechanical act of scratching acts on pressure, and of course, the slight pain caused by the action leads to the release of the “happy hormone” serotonin.
Nevertheless, the whole act of scratching is known to evoke a positive response via the Reward System. This is why you feel extra good after scratching your back, as it aids in releasing pressure.
Hence, scratching your back is like a ‘mini-massage’ that temporarily eases any tension you might be feeling. So, the next time you get tired, but are still chained to your desk, you know exactly what you should do!