Many people have an interest in understanding the root cause of mood disorders and mental illnesses. Those who suffer from them, those who treat the sufferers and the family members affected, to name a few.
Another group with a keen interest in the underlying causes of these conditions is researchers. And these folks might be getting a little closer to an answer.
Psychiatrists have long believed that genetics, trauma and neurochemical imbalance combined to cause mood disorders like bipolar disorder, major depression and even schizophrenia. Now, another aspect comes to light, which appears to have a significant role in the development of these challenging conditions.
Sleep. Or rather, a lack of it. But that’s an oversimplification. Specifically, disrupted circadian rhythms are what researchers at the Institute of Health and Wellbeing at the University of Glasgow were looking at.
Their study, recently published in the Lancet Psychiatry, was a huge study, incorporating data from over 90,000 people from the UK, all aged 37-73. They were part of a long-term research project by the Biobank. According to the Biobank website, they are investigating “…contributions of genetic predisposition and environmental exposure to the development of disease.”
Participants wore an activity and movement tracker 24 hours a day for a week. The AX3 triaxial accelerometer is similar to a FitBit or other fitness tracker.
Researchers were tracking how active, passive or intensely active each participant was during the day and at night. Participants also filled out a health questionnaire. Data from the accelerometer was cross-referenced with the questionnaire.
For those with mood disorders, sleep disruption is a common companion. What scientists have always wondered is: does a mood disorder disrupt sleep or does disrupted sleep cause a mood disorder or make it worse?
To try to prevent research bias, the researchers kept those with reported sleep disorders and sleep apnea out of the study.
What they discovered was that those who were more active at night and less active during the day seemed to have a higher risk for bipolar or major depressive disorder, across their lifetimes. They also seemed to be lonelier, less happy, more neurotic and more prone to mood instability.
Those with mood disorders and up at night tended to be men, tended to have higher BMI, lower education levels and were likely to have suffered a childhood trauma. The association between depression and circadian rhythm disruption has been so persistent and so strong that some experts have suggested replacing the designation depression with depression-insomnia complex.
Interestingly, a 2010 study discovered that bipolar children had a mutated RORB gene. This gene is responsible for regulating circadian rhythm. Another study in 2013 revealed that depression disrupted the portion of the brain responsible for control of circadian rhythms.
This study, however, is the first to provide evidence of a direct link through live behavioral data.
The study was well designed and executed, with the exception of one significant limitation. The monitoring period was only one week.
Were these people experiencing first-time or only occasional circadian rhythm disruptions? Do they have the same issues throughout each month or throughout the year?
Obviously, further research will be needed to verify these findings. If there is a definitive link between disrupted circadian rhythms and depression, bipolar disorder and/or other mental illness, that would be a finding that fills a gap in current theory.
If we can recalibrate circadian rhythms and help mood disorder sufferers, we might be able to save billions of dollars AND improve the lives and outcomes of so many sufferers.