Why do people shiver when they feel cold, are they excited or frightened? The brain is said to release two hormones which are Norepinephrine and Epinephrine. These two hormones are liable for increasing breathing and heart rate, at the same time constricting certain blood vessels, mainly those in the digestive system and the skin, especially when the person is exercising.
These two components of the brain have an effect on the reactions of people. They show different reactions and emotions in different situations, for instance when people are sick or nervous, they shiver. It is believed that anxiety is a usual reaction to stress. If people are stressed because of their sickness, they tend to show some reactions. Some people use anxiety to deal with a tricky situation. They are able to cope with difficult situations whether at school or at work. Shivering could go together with physical effects such as chest pain, nausea, palpitations, and shortness of breath, head and stomach aches. Physically, the body will prepare the organism to cope with the threat.
Heart rate and blood pressure are increased, the blood flow to the main group of muscles are increased, sweating is increased and the functions of the digestive and immune system are inhibited, which can either show a flight or fight response. The external signs of shaking and anxiety can include papillary dilation, trembling, sweating and pale skin. A person who is going through shivering can experience this as a sense of panic or dread as well. Being frightened is also a reason why people shiver. Some shiver because they are frightened when their life is at risk. In addition, people shiver when they are cold or when excited. When you have a reaction of fear in your body, you will obtain a rush of the hormone adrenaline which will lead your body to react more rapidly in a stressful condition. Adrenaline can possibly dilate the pupils, speed up your heart beat so your body is more capable to ‘flight or fight’.
In relation to this, your body will switch from storing glucose, because other chemical energy stores found in your tissues discharge them in order to give the muscles the extra needed energy to hard labor in combination with the improved oxygen. As a result, the chemicals and stimuli in your body have drastically shifted. The movement will be harder to control and become more erratic. This is actually the result of the causes why people shiver to show different reactions.