What is anxiety?

Anxiety is a normal emotion. Everyone has anxiety on occasion. It is the emotion that people have when something dangerous might happen. Anxiety is closely related to fear. Fear occurs when something dangerous is happening. Anxiety, though, occurs when something dangerous is pending, and hasn’t happened yet, though it could.  

Anxiety can be divided into different aspects: feelings, physical manifestations, thinking, and behaviors.

A number of feelings are associated with anxiety:

  • Apprehension
  • Alarmed
  • Tension
  • Nervousness
  • Doubt in one’s abilities
  • Aimlessness

Corresponding to these feelings, people with anxiety also commonly have the following physical manifestations:

  • Muscle tension
  • Increased perspiration
  • Increased heart rate & blood pressure
  • Gastrointestinal urgency, followed by an upset stomach
  • Increased energy and even shakiness
  • Cold hands & feet

Specific ways of thinking also occur when anxious:

  • Worry
  • Increased focus on the possible danger and all its consequences
  • Thinking about the worst-case scenarios of what might happen (otherwise known as catastrophizing)

When having all these anxious experiences, people tend to behave in specific ways. They are often:

  • Restless
  • Avoidant of activities (particularly those activities that bring about the possible danger)
  • Stay at home
  • Have difficulty completing activities or projects

Sometimes, anxiety becomes persistent. It can then become impairing. It gets in the way of living day to day life. When anxiety is persistent and impairing, it’s considered no longer normal, but rather a disorder.  

Anxiety and the nervous system

Anxiety is a state of the autonomic nervous system. When anxious, people are literally nervous. They are nervous in their feelings, their body, their thinking and in their behavior.  As such, the nervous system is in a heightened state of alarm. The state of alarm is set off by the possibility of a dangerous thing happening.

Psychologists have dubbed this state of alarm the fight-or-flight response. It prepares people for action, for meeting the challenge of the dangerous thing that might happen. To meet these challenges, the nervous system responds with feelings of being alarmed, with physical changes that increase the capacity for action, with an increased cognitive focus on the possible danger, and avoidance behaviors.  

If the danger were actually occurring, this fight-or-flight response of the nervous system would be quite helpful. It would allow for fear-based responses and escape behaviors. In the case of anxiety, the danger isn’t actually happening, but simply might happen. The nervous system prepares by going into fight-or-flight nonetheless. The same responses occur, but the accompanying avoidant behaviors become less goal-directed. In fact, the avoidant behaviors associated with anxiety are in the end quite restless, unproductive and aimless.

The relationship between anxiety and chronic pain

Anxiety is quite possibly the most common condition that accompanies chronic pain. Anxiety tends to go hand in hand with chronic pain. The reason is that pain is a danger signal. The function of pain is to signal danger that something is wrong in the body and requires attention. As such, pain is a warning signal that naturally leads the nervous system to respond with its corresponding alarm – the fight-or-flight response.

The nervous system’s response to pain neatly corresponds to its response to any other danger.

  • Feelings of alarm, apprehension and distress
  • Increased reactivity of the body, such as increased muscle tension, increased heart rate ad blood pressure, gastrointestinal reactivity, and the like
  • Increased cognitive focus on the danger, in this case, pain, and a tendency to worry and catastrophize about it
  • Avoidance behaviors, such as guarding, resting, staying home and not engaging in activities that might bring about or increase pain

In acute pain, these responses might be quite helpful. The corresponding fear allows for seeking help and guarding in order to prevent further injury. In chronic pain, they become anxiety and avoidance behaviors.

In the case of chronic pain, the anxiety and avoidance behaviors become chronic themselves. The chronic anxiety leads to a chronic sense of alarm or distress, which makes patients edgy. Cognitively, it leads to a chronic focus on pain, which pre-occupies the attention of the pain sufferer. Everyday decisions seem to turn on how much pain the patient has at any given time. It also leads to chronic muscle tension, which in turn leads to more pain. Chronic avoidance behaviors subsequently lead to an increasing sense of social isolation, inactivity, de-conditioning and, ultimately, disability.

The common denominator between chronic pain and chronic anxiety is the nervous system. The nervous system has become stuck in a persistent state of reactivity. This state of reactivity is associated with a condition called ‘central sensitization.1, 2, 3, 4 Central sensitization is, at least in part, the process by which acute pain becomes chronic pain.5, 6, 7, 8 As such, anxiety tends to go hand in hand with chronic pain.

Treating anxiety in chronic pain rehabilitation programs

Chronic pain rehabilitation programs are the only form of chronic pain management that makes it a point to also focus on treating anxiety. In such programs, patients acquire the abilities to self-manage pain, return to work, and overcome any complications like anxiety.  

Chronic pain rehabilitation programs routinely utilize the most effective treatments for anxiety, such as cognitive behavioral therapy, antidepressant medications, and mild aerobic exercise.  

It is possible to learn to live well despite having chronic pain, and in the process overcome anxiety.


1. Yunus, M. B. (2007). Fibromyalgia and overlapping disorders: The unifying concept of central sensitivity syndromes.  Seminars in Arthritis & Rheumatism, 36, 339-356.

2. Ji, G., & Neugebauer, V. (2007). Differential effects of CRF1 and CRF2 receptor antagonists on pain-related sensitization of neurons in the central nucleus of the amygdala. Journal of Neurophysiology, 97, 3893-3094.

3. Meeus M., & Nijs, J. (2007). Central sensitization: A biopsychosocial explanation for chronic widespread pain in patients with fibromyalgia and chronic fatigue syndrome. Clinical Journal of Rheumatology, 26, 465-473.

4. Martinez-Lavin, M.  (2007).  Biology and therapy of fibromyalgia: Stress, stress response, and fibromyalgia.  Arthritis Research and Therapy, 9, 216.

5. Rivat, C., Becker, C., Blugeot, A., Zeau, B., Mauborgne, A., Pohl, M., & Benoliel, J. (2010). Chronic stress induces transient spinal neuroinflammation, triggering sensory hypersensitivity and long-lasting anxiety-induced hyperalgesia. Pain, 150, 358-368.

6. Chen, Y. (2009). Advances in the pathophysiology of tension-type headache: from stress to central sensitization. Current Pain and Headache Reports, 13, 484-494.

7. Blackburn-Munro, G., & Blackburn-Munro, R. E. (2001). Chronic pain, chronic stress, and depression: Coincidence or consequence? Journal of Neuroendocrinology, 13, 1009-1023.

8. Imbe, H., Iwai-Liao, Y., & Senba, E. (2006). Stress-induced hyperalgesia: Animal models and putative mechanisms. Frontiers in Bioscience, 11, 2179-2192.

Date of publication: March 20, 2015

Date of last modification: March 14, 2021


Murray J. McAllister, PsyD, is a pain psychologist and consults to health systems on improving pain. He is the editor and founder of the Institute for Chronic Pain (ICP). The ICP is an educational and public policy think tank. In its mission is to lead the field in making pain management more empirically supported, the ICP provides academic quality information on chronic pain that is approachable to patients and their families. 

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