Many patients living with chronic pain admit that their symptoms worsen at night. A logical assumption would be because they have done a lot of activity during the day that has stressed their body… hence the night pain.
However, they may also admit to little association between their activity level during the day and the pain waking them up at 1am.
The fact is that nothing is structurally different at 2am versus during the day; so why the pain?
A physiological explanation for night pain could be justified by various hormonal and cortisol level changes that happen based on our circadian rhythm.
For example, cortisol has been shown to have anti-inflammatory effects, and its levels drop at nights. Therefore, pain can increase as the body’s natural anti-inflammatories are at their lowest.
“Cortisol is a potent anti-inflammatory that functions to mobilize glucose reserves for energy and modulate inflammation… prolonged or exaggerated stress response may perpetuate cortisol dysfunction, widespread inflammation, and pain.” – Hannbal et al 2014
Another possible explanation for worsening night pain is our brain’s capacity to pay attention to the pain.
Think of it, during the day the brain is busy looking for food, drink, moving and completing a to do list of things… you may say the brain is “too distracted” to focus on danger signals from the body.
However, when the to-do list is put aside and you are finally ready to relax, the brain can now decide to pay attention to possible danger signals with greater attention.
Sometimes symptoms increase at night because the brain’s awareness of them increases when things get quiet. In the silence of their own thoughts, the brain can start scanning the body for any threats such as replaying old injuries or creating new ones assumed happened during the day.
For some people, just being still threatens their nervous system hence they do anything to keep busy, be it work, exercise or aimlessly scroll on the phone.
It is in that stillness, be it during the day or at night, is when the brain can become hyperaware of all the happenings in the body including perceiving pain.
With repetition, the brain becomes conditioned to associate being still during the day or at night as a predictable threat, triggering stress and pain.
This pattern can sadly become a routine and present itself right on schedule at 2am when you want to be asleep… though it doesn’t make sense, the familiar night pain becomes the “safe space” for the brain as it is predictable.
“…poor sleep has been linked to higher levels of disability, depression, and pain-related catastrophizing.” – Jain et al 2024