Do I Have a High or Low Pain Threshold?
Firstly, let’s start with what pain is:
Pain is defined as an unpleasant sensory and emotional experience that is associated with actual or potential tissue damage or that is described in terms of such damage.
Nerves are wires that conduct electronic impulses around the body to enable movement, vital functions and sensation.
Regarding sensation, nerves produce feelings of pleasure, fear and pain.
Nerves around your skin have different types of receptors to survive in the outside world, pain is a fundamental mechanism of survival because it allows you to learn (the hard way) what elements to avoid.
The nerves carry transmissions through sodium/potassium balances which creates a positive charge, carrying the signal down the nerve. Eventually, this signal jumps the to the next nerve cell through a process called synaptic transmission. During this process, the signal can be blocked or amplified. This is important because it is the reason why we sometimes don’t feel pain (like running away from a threat with adrenaline pumping) or it is heightened (like when we are expecting to get hurt). This brings us on onto central sensitisation.
Central sensitisation is where the body goes to a constant state of high reactivity, typically associated with chronic pain and illness.
The sensors in the skin that enable us to feel touch and pain have relatives all around the body (taste/balance/hearing etc), sometimes these sensors are upregulated, typically due to trauma, which produces the centralisation effect.
As a result of this, the somatosensory cortex in the brain picks up these stronger than normal signals and becomes sensitised. This creates a feedback loop and becomes difficult to untangle.
Reasons for variables in pain threshold
Lack of sleep can lead to an increase in infection, migraines, reduced athletic performance and reduced mood. It can also lead to increased pain perception.
Sleep/pain relationship may be bidirectional (so pain leads to lack of sleep and lack of sleep leads to pain).
However many studies have found a positive correlation between lack of sleep and reduced pain tolerance.
One study, in particular, showed that lack of sleep leads to a huge 24% increase in pain sensitivity.
In some people, they have a gene that, when expressed, can lead to ‘over-methylation’ of the nerves, which leads to increased dopamine and adrenaline, which causes hyper-arousal, reduces sleep and increases sensitivity to stressors, contributing to pain. This research suggests that stress affects everyone differently and if you are unfortunate enough to have these genes, you won’t tolerate stress well which leads to increased pain perception.
Emotion can help to modulate pain through an interaction of pleasant-unpleasant (emotion) and calm-excited (arousal) emotions. Typically, negative emotions evoke anxiety and increase pain.
At the top of the brain stem lies the thalamus, a part of the brain that is known as the ‘relay station’, because every sensation (apart from smell) runs through it as it sends the sensations to different parts of the brain. Stressful situations are perceived and distributed via the thalamus to parts of your brain that keep you alert to the threat – staying alert means you need to be sensitised to increase pain perception so you can get into fight or flight mode quicker. Referring back to central sensitisation, in some people, this response doesn’t calm down.