This happens due to thought processes when the body is tired and the confused nervous messages send to the brains through tired nerves. Thoughts of going mad is only perceived because of the reduced oxygen level to the brain which can affect your mood. Madness in mental illness is not perceived whereas in the case of anxiety panic attack, the thought processes come back to normal when the attack is over. 

During anxiety and panic attacks, the muscular tension around the sheath of muscles covering the skull causes a feeling of being tightly banded around the head. This is because there is restricted blood circulation around these tissues during anxiety attack. Also tension around the neck, arms and back can cause severe migraine type of headache. All these will go away once the anxiety panic subsides. 

During anxiety and panic attack, you may become irrational with the feeling of having to do things faster or to speak faster and do things that you normally would not do. This happens because you are confused and afraid during anxiety attack but this is only a passing sensation and will go away.

These sensations are caused due to the confused nerves during anxiety and they can not harm you. The nerve endings on your body are filled with electrical impulses and therefore you may feel tickling sensations or being pricked by pins and needles.

Although quite harmless, the abnormal nerve impulses in the body can create these strange sensations and it can be quite distressing. However, there is nothing to worry about as this is just the reaction of the nervous system which has a complex network of electrically charged nerves throughout the entire span of your body.

Shaking occurs when there is a drop in the body temperature and is a normal reaction to fear or the cold. When the muscles spasmodically contracts there is a friction between the body tissues and the muscles and this produces the sensations of shaking. During anxiety, this is quite a normal symptom as the friction causes the body to heat up and raises the body temperature. These shaking and shivering sensations will go away as soon as the body temperature returns to normal.

Your mouth may feel dry during anxiety and this happens because the fluids are diverted to other parts of the body during anxiety attack. You need to stay calm and sip some water or have sweets to keep the mouth lubricated. This dryness will go away when the anxiety subsides.

During anxiety attacks, the body prepares itself for fight by releasing sweat to cool down the body temperature. As the sweat works up and evaporates, the body begins to cool down. When the anxiety level slowly subsides, the sweating also begins to return to normal. This is a usual symptom without having much to worry about.

This is a natural sensation during panic attacks and it may feel like you are having a heart attack. This is caused by muscle tension and therefore the chest may start hurting but this is different from heart pain and you must not panic. By having someone massage the tensed upper back muscles and arms and also by deep breathing exercises, such unpleasant sensations will slowly go away.

These feel as if the heart is racing and missing beats and sometimes slows down as if it will stop beating. However this is the work of adrenaline that is released into the blood stream during anxiety which causes these sensations. These sensations will not harm you or cause death. They will go away eventually if you try to stay as calm and as relaxed as possible. 

These distressing sensations will generally feel like your chest cannot expand enough to take in air or that someone is trying to smother you with a pillow. It is important to remember that this will not kill you as it is only caused by exaggerated nerve impulses and the sensations will go away. You need to keep calm and try to breathe easy.