Chronic pain has a profound and far-reaching impact on the lives of many Canadians. With over 20% of our population living with some form of chronic pain, it’s vital to take the time to better understand the chronic pain experience; for a lot of people, part of this experience involves the concept of disability. Watch the third installment in our Summer 2023 video series about chronic pain as a disability to learn more.

Special thanks go out to one of the amazing PWLE on the CircaPain team, Lesley, who came up with the idea for this video, and to Emily, our summer public health practicum student, who is the creator of this video series.


Video produced by Emily S.


The dawn of the 21st century brought along with it the popularization of ‘personalized medicine’; the tailoring of someone’s medical care and treatment to suit their individual needs and genetic predispositions. As a team of people researching circadian rhythms, we are very interested in using personalized medicine to target our circadian system; a strategy called ‘chronotherapy’.

Never heard of chronotherapy before? Well that’s okay because we have created an introductory video about it as the second installment in our Summer 2023 video series.


Video produced by Eileen D. and Emily S.

In our new video series, we’ll be discussing a bit of the key concepts that drive our research. Naturally, we had to start with chronic pain as it is so central to our study and its goals. Watch the video above to learn a bit more about chronic pain.

The CircaPain study is open to all eligible participants – get involved today by clicking on the “Participate” tab!


Video produced by Eileen D. and Emily S.


Want to learn more about CircaPain but don’t know where to start? Check out this short video where we take you through the basics of our study and why it’s so important. If you still have questions, check out our FAQs or email us at You can find the survey itself by clicking here.


Written by Hailey G.


What is Multiple Sclerosis?

Multiple sclerosis (MS) is a chronic autoimmune disease that affects the central nervous system. MS targets myelin, which is the insulating layer of the nerves that allows electric signals to transmit more efficiently. While symptoms differ from person to person, multiple sclerosis usually manifests as weakness in the limbs, vision problems, slurred speech, fatigue, and dizziness. Here in Canada, where Circa Pain is based, we have one of the highest reported rates of MS worldwide. One estimate reveals that 1 in every 400 Canadians is living with the disease (Statistics Canada, 2018). No definite cause of MS has been determined to date. However, some risk factors that increase MS incidence have been found, such as genetics, smoking, and sex.

Multiple Sclerosis Incidence and Latitude

Newer research suggests that latitude might be another risk factor that correlates with MS incidence. One study conducted at the University of Tasmania, Australia found a notable association between MS severity and latitude (Tao et al, 2021). The researchers used age of disease onset as a marker for MS severity (with earlier onset being more severe) and found that the onset of symptoms was on average two years earlier for those living at higher latitudes. This finding echoes an older Australian study conducted in Queensland that also found a significant relationship between latitude and MS prevalence (Hammond et al, 1987).

However, a study within Asia found that geographical latitude was not a factor affecting the prevalence of MS (Zhang et al, 2020). The researchers conducted a meta-analysis of epidemiological data of MS from China, Japan, and neighbouring countries. They found that there was no correlation between geographical latitude and MS prevalence in those populations. As such, more studies need to be conducted to determine whether latitude or another underlying factor, such as exposure to sunlight, is behind the observed correlation in the Australian studies.

How the Latitude-MS Correlation Relates to Our Work

People living with multiple sclerosis experience different levels and types of pain, such as tingling, sudden pain spasms, or chronic muscle/joint pain. We are particularly interested in the work done in the aforementioned studies since the latitude at which you live determines how many daylight hours you are exposed to. This, in turn, can disrupt the body’s natural circadian rhythm, which is a term that describes the collection of biological functions that follow the 24-hour cycle (read more about circadian rhythms here). This is where our lab group comes in. In our work, we are looking to determine if circadian disruption plays a role in the experience of pain. To learn more, read about our research here.


Written by Tima Al-Shammaa


1. Hammond, S. R., et al. (1987). The epidemiology of multiple sclerosis in Queensland, Australia. Journal of the neurological sciences, 80(2-3), 185–204.
2. Multiple sclerosis: Prevalence and impact. (2018, January 17). Statistics Canada.
3. Tao C, et al. Higher latitude is significantly associated with an earlier age of disease onset in multiple sclerosis, Journal of Neurology, Neurosurgery & Psychiatry 2016; 87:1343-1349.
4. Zhang, et al. (2020). Incidence and prevalence of multiple sclerosis in China and other Asian countries (Barcelona, Spain), S0213-4853(20)30269-3. Advance online publication.

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We’re almost two months in since the launch of CircaPain. Gaining new participants every day, we are looking forward to what the next few months will bring. This week, the principal investigator of CircaPain, Dr. Nader Ghasemlou, sat down with Alan Neal of CBC Radio One’s All in a Day to talk about the origins of our study and its ongoing recruitment.

CircaPain evolved from previous work done by the Pain Chronobiology & Neuroimmunology Lab at Queen’s University, investigating pain fluctuation in people living with chronic low back pain. We found that some participants had constant pain, whereas others had pain that was reliably lower in the mornings and more intense at night (“circadian pain”). With CircaPain, we want to find out if these patterns are experienced by people living with different types of chronic pain and why they might occur. Since everyone’s experience with chronic pain is different, it’s crucial that we have as many people as possible participate in CircaPain to further our understanding of this complex topic.

To learn more about the study, check out our FAQs. If you have any questions, feel free to reach out to us at

Listen to the full interview here: All in a Day with Alan Neal


Written by Hailey G.

CircaPain was developed by a team of scientists, clinicians, and people with lived experience from across Canada. Part of our team works at Queen’s University and was able to chat with the folks at Global News Kingston about our exciting new project. Click here to read their article.

Still have a few questions about CircaPain? Check out our FAQs or email us at – we are more than happy to help you!


Written by Hailey G.


Curious about the people working on CircaPain? Sit down and listen to our fantastic patient partners (Mary B., Jennifer DC., and Lesley NS.) talk about the study and how it came to be.

The CircaPain study is now open to all eligible participants – get involved today by clicking on the “Participate” tab!


Written by Hailey G.

What are Circadian Rhythms?

The word “circadian” originates from the Latin phrase circa, meaning “about”, and dies, meaning “day, which means the rough translation of circadian rhythm is “about the days rhythm”. The study of circadian rhythms falls under the science known as Chronobiology.

Chronobiology is the study of biological rhythms including, but not limited to sleep/wake cycles, respiration, heart rate, blood pressure, body temperature, mental function, nerve activity, hormone regulation, and activities at the cellular level. Circadian rhythms are a subtype of chronobiological rhythms with 24-hour cycles. Other chronobiological rhythm subtypes include infradian rhythms that are on greater than 24-hour cycles, such as seasonal rhythms and ultradian rhythms that are less than 24-hours.

How Does Light Exposure Affect Circadian Rhythms?

Although circadian rhythms are internally produced, they adjust to the local environment based on external factors including temperature, eating patterns, and exposure to light. Light enters our eyes and then neurons in our eyes send signals to our brains allowing us to perceive vision. Other neurons will send signals to another part of our brain known as the suprachiasmatic nucleus (SCN), which is a cluster of neurons that lies just above the crossing of the optic nerves. The SCN is known as “the master clock” and its regulation by light stimulation will entrain the body’s internal circadian rhythm to coincide with external light/dark cycle cues. This is why we feel awake and are active during the days and feel tired and go to sleep during the nights.

SCN: The Master Clock

The SCN is the body’s control center of circadian rhythms. It generates circadian outputs that affect the rhythmic activity in almost every tissue and cell in the body. The SCN sends hormones and other mediators which can change the expressional patterns of specific genes, known as “clock genes” that affect circadian rhythms of the body’s many tissues and cells.

Why are Circadian Rhythms Important?

Circadian rhythms govern all of our biological processes and we need them in order to function properly. Evidence for this is seen with sleep disorders and aggravated disease states arising from circadian disruptions.

What is pain?

Pain is an unpleasant sensation with both physical and emotional components. Pain comes in many forms and is often used as a symptom relating to a disease state of an individual. We feel pain due to the activation of sensory neurons, known as nociceptive neurons, that send signals to the brain indicating pain. In addition to the nervous system, cells and mediators of the immune system play a role in the sensitization of nociceptive neurons in the cases of inflammation and injury related pain. There are two major types of pain disorders: nociceptive pain which arises due to non-neural tissue damage; and neuropathic pain that is due to damage or altered functioning of the nervous system.

Chronic Pain

Pain can either be acute (lasting for a short amount of time) or chronic (lasting for longer periods of time – typically 3 months or more). There are many different types of chronic pain including cancer related pain, arthritis, headache, fibromyalgia, low back and neck, and posttraumatic pain.

Circadian Pain

Many types of chronic pain have been shown to have fluctuations in the intensity of pain reported from patients that follow a circadian (24-hour cycle) rhythmic pattern. This is an emerging field of study where new rhythmic patterns are being described for various types of pain including rheumatoid arthritis, fibromyalgia, and multiple sclerosis related pain. Identifying these pain patterns could provide clues to the underlying cause of this phenomenon as well as help us better understand the modulation of ongoing pain.

The Link

The definitive explanation as to why there is an observed circadian rhythmicity in certain chronic pain types of chronic pain is still being uncovered. Since circadian rhythms are involved in so many biological processes it is likely that there is a combined effect of multiple systems involved.

Circadian rhythms have been linked to play a part in the sensitization of peripheral and central nociceptive neurons which mediate the pain response. Additionally, cells and mediators of the immune system, involved in sensitization and/or inflammation causing a pain response, are under circadian control. Some of the cells of interest are microglia and astrocytes, which are found in the central nervous system (brain and spinal cord), as well as lymphocytes, which infiltrate to the site of injury and cause inflammation and nociceptive hypersensitivity.


Circadian rhythms are involved in virtually all biological processes within the body, including some forms of chronic pain. This observation has important implications to future research and treatment of pain. Further investigation into the role that circadian rhythms play in the regulation of neuroimmune cells and mediators of pain is necessary. This may help to better characterize these phenomena and help develop therapeutic strategies to treat chronic pain more effectively.



Written by Bruce M.

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