Many people living with persistent pain notice that their symptoms follow a pattern throughout a day. Morning stiffness, evening flare-ups, or fatigue that intensifies through the day are common experiences - but not often addressed very well in treatment. These patterns reflect underlying biological rhythms, and emerging research is beginning to clarify the mechanisms involved.

Circadian pain patterns in human pain conditions - A systematic review — A 2023 systematic review in *Pain Practice*, which surveyed 39 clinical studies, makes clear that, for many conditions, pain actually follows a circadian cycle - a 24‑hour rhythm tied to hormone secretion, immune activity, nerve signalling and sleep.

Pain Rhythms Vary by Condition

The review analysed 39 human studies across a broad range of presentations - including postoperative pain, fibromyalgia, osteoarthritis, migraines, and neuropathic pain. Each showed distinct temporal patterns:

Postoperative pain was consistently more intense in the morning, a trend possibly linked to early-day increases in cortisol and pro-inflammatory markers.
Fibromyalgia pain peaked on waking. Those with Fibromyalgia show disrupted melatonin rhythms, producing more of it during the day instead of at night - this shift is linked to poorer sleep, more pain sensitivity, and feeling less rested in the morning.
Osteoarthritis pain tended to rise through the afternoon and evening, although mechanisms were not clearly defined. This suggests that the timing of physical activity and joint loading may influence daily symptom severity.
Neuropathic pain, such as diabetic neuropathy or post-herpetic neuralgia, often worsened as the day progressed. Importantly, this pattern persisted even in participants receiving analgesic treatment, indicating a rhythm driven by internal regulation rather than medication alone.
Migraine onset was commonly reported in the early morning hours, potentially reflecting neurochemical shifts involving serotonin and melatonin.
Cluster headaches were most likely to occur at night, particularly around 2:00 am, with hypothalamic dysregulation (the brain’s circadian control centre) noted as a likely contributor.

Why This Matters for Pain Rehabilitation

When someone’s pain flares at the same time each day, it's often interpreted as behavioural/circumstantial - e.g. walking too far one morning, drinking too much coffee later in the day. But this review highlights that for many conditions, pain can flare for deeper physiological reasons.

Reasons we need to understand and appreciate in order to find:

More effective pain relief
More consistent functional improvement

For example; If pain peaks every morning, we need to ask: is that the right time to load a joint, or to test a new movement? If someone reports evening flare-ups, is it due to what they did - or when they did it?

This matters when we're trying to build sustainable routines. When to challenge, when to rest, when to plan pacing - all of it becomes more workable when we understand that pain itself is fluctuating.

A Time-Aware Approach to Pain

Most rehab plans focus on what to do - strengthen this, stretch that, change how you move. Less often do they ask when. But if pain itself fluctuates across the day, then timing of the rehab strategy is just as, if not more important than the strategy itself.

This doesn’t mean chasing the perfect time of day to exercise. It means recognising that your system may be more reactive at certain times, or more resilient at others - and working with that, rather than pushing against it.

Take fibromyalgia, for example. People often describe waking up already sore, foggy, and tired, even after sleep. This paper suggests this may be tied to disrupted melatonin rhythms - producing more during the day than at night - which can dull the body’s ability to rest and restore. In that context, asking someone to do their most strenuous rehab work first thing in the morning might not be the best fit.

Or consider someone with neuropathic pain, whose symptoms worsen as the day progresses. In this case, we would try and schedule highest exertion rehabilitation work for early in the day.

These kind of adjustments are a necessity in good chronic pain rehabilitation, and necessitate some form of symptom tracking. A flare-up at 6pm doesn’t always mean “you overdid it.” It might mean your system is following a rhythm you haven’t mapped yet.

This is where symptom tracking can be seen as a process of helpful curious discovery and less as a painful chore that heightens our stress. Simple notes about when pain or fatigue shows up - morning versus afternoon, pre-meal versus post-exertion - can reveal patterns that may not be obvious day to day. But over a week or two, they start to build a clearer picture of your body’s rhythms.

It’s not about obsessively recording everything, or chasing control. It’s about giving yourself and your treating team better data. Once those rhythms are visible, we can work with them. We can time activity more deliberately, adjust expectations across the day, and begin to match rehab strategies to your physiology.

Reading this article was quite validating as this ‘time-aware reasoning’ already shapes how I support people with complex pain and invisible illnesses. Whether you’re living with Osteoarthritis, Fibromyalgia, Long COVID, POTS or any other condition, just noticing how your body shifts throughout the day can help a lot. By paying attention to timing, we’re not only better able to reduce flare-ups - we can also create space for more stable function, more confidence, and less fear around doing “too much.”

If you’re managing persistent or fluctuating symptoms and are curious about how to better make sense and manage them, submit a message or enquiry here.

Reference

Knezevic, N. N., Nader, A., Pirvulescu, I., Pynadath, A., Rahavard, B. B., & Candido, K. D. (2023). Circadian pain patterns in human pain conditions–A systematic review. Pain Practice, 23(1), 94-109. https://doi.org/10.1111/papr.13149