• Núria Estapé, science journalist

    Skin-deep emotions

    13 Apr

    Our skin reveals our feelings to the world. The face is said to be the mirror of the soul. And the skin of the face never lies. We blush when we feel embarrassed, we get goosebumps when we feel strong emotions and we break out in a sweat when we are scared or nervous. All these reactions, reflected in the skin, give us away. We have no control over them.

    Picture the skin as a sponge that absorbs sensations rather than water. And picture the skin as a mirror, except that, unlike a mirror reflecting images, the skin reflects our feelings and the internal reactions of our bodily organs, especially our brain.

    Several studies have demonstrated how feelings and emotions activate fibres in the autonomic nervous system that send information to the cells of the skin. Such reactions are called visceral reflexes. Let’s see how they change the appearance of the skin.


    The blush of embarrassment

    Someone unexpectedly compliments us and we immediately blush. Our cheeks and ears become flaming red. Once we notice this or it is pointed out to us, we get nervous and blush even more deeply.

    What’s going on? The brain interprets the compliment as an emergency situation and, without us even being aware that this is happening, sends signals to blood vessels (small arteries) in the skin to contract. This, in turn, makes the blood circulate faster. Adrenaline released from the adrenal glands increases our blood pressure and the inevitable result is reddened skin.



    Cold, fear and other strong emotions have almost certainly caused our skin to bristle at one time or another. This is a reaction inherited from birds and mammals, our feathered and furred ancestors.

    As happens with blushing, the brain tells the muscles in the skin to contract. These small muscles, called arrectores pilorum, cause the hairs on our skin to rise, a reaction known as piloerection or horripilation. Although the latter name seems ‘horrific’, fear in humans is not the main cause. Nor is cold a main cause, as this skin reaction in birds helps keeping their bodies warm.

    What emotions cause goosebumps in humans? Researchers asking this question analysed how hair reacted to a wide range of situations and demonstrated that feeling emotional (about music, a speech, a gesture, etc) was the most likely cause of this reaction in people.


    Hot and cold sweats

    We have just received some bad news. Our fear paralyses us and we feel cold sweats breaking out all over our body. Our involuntary nervous system (which we cannot control) has mobilised so much energy to overcome the shock that it almost fails to pump blood, with the result that we go pale or feel faint. Blood is one of our main sources of energy. When we are scared, it is as if the blood drains from our face because other organs, such as muscles, need it more.

    But why do we sweat? Sweating is another involuntary response, caused by the triggering of our sympathetic nervous system (a branch of the involuntary nervous system that controls the viscera). When we sweat we do so because the skin receives orders from nerve fibres to activate the sudoriferous glands located under the skin that contain the fluid we call sweat.

    Anxiety itself also causes sweating. Skin dampened with sweat conducts electricity better – so much so that a test that measures the amount of electricity passing through the skin can tell if a person is lying. The skin always reveals the truth. We can, like actors, train our face and our words to express something we do not feel. But the skin cannot pretend and cannot lie.

    We also sweat when we eat spicy foods. Spices contain a substance called capsaicin, which activates pain and temperature nerve endings in the mouth that trick the brain into believing that the body’s temperature is increasing dangerously. Sweat is therefore released to dissipate body heat. When we eat spicy food, therefore, the sweating is the response of a deceived brain.


    A glass of wine

    But it is not only spices that alter the appearance of the skin. When we drink wine, it is normal for our skin colour to rise. However, the cutis (the skin of the face) experiences the direct consequences of a peculiar allergic reaction: alcohol intolerance.

    People of Asian origin are more prone to this reaction, which also produces cutaneous flushing, sometimes very intense and accompanied by itching. What makes some skins ‘allergic’ to alcohol? For genetic reasons, around half of the Chinese, Japanese and Korean populations lack the enzyme (aldehyde dehydrogenase) needed to metabolize alcohol. Without this enzyme, alcohol is toxic for the body.


    Emotions and stress

    Intense ongoing emotions change the appearance of the skin, which sometimes is damaged as a result. This is the case of emotional stress. Another blog post describes how stress can trigger or worsen ailments such as eczema and psoriasis.



    Experimental Dermatology