You may be quite familiar with the effects of anxiety -- heart pounding, stomach churning, hand shaking -- but you may be less familiar with what causes anxiety.
Animals, including humans, react to perceived threats by going into a state of hyperarousal called the fight-or-flight response. During this response, hormones are secreted that act to prepare the body to take action against those threats.
Some of the physical effects of this response include:
- Accelerated heart rate
- Accelerated breathing
- Paleness or flushing of the skin, or a fluctuation between the two as blood is shunted away from the skin surface to the skeletal muscles
- Slowed or stopped digestion
- Changes in tension in the bowel and bladder sphincter muscles; bladder relaxes and colon may evacuate
- Constriction of blood vessels
- Nutrients are freed up for use by the muscles
- Increased sweating in order to cool the body
- Dilation of blood vessels supplying the muscles (to allow for more flow of nutrients and oxygen)
- Inhibition of lacrimal gland (responsible for tear production) and salivation
- Dilation of pupil
- Inhibition of erection
- Loss of hearing
- Tunnel vision (loss of peripheral vision)
- Acceleration of instantaneous reflexes
If you are preparing to fight a foe or run for your life, these adaptations can be quite useful. In one way or another, they prepare your body to take quick action. Unfortunately, for those of us living in modern times, we are more likely to be worried about losing our jobs than fending off a hungry lion. Instead of helping us to survive, these physical changes cause the symptoms that we recognize as anxiety, such as poor sleep, loss of appetite and nervousness.
Sources:
Gleitman, Henry, Alan J. Fridlund, Daniel Reisberg. Psychology 6th ed. NY: Norton, 2004.
Noble, John M. et. al. eds. Textbook of Primary Care Medicine 3rd ed. St. Louis: Mosby, 2001.
