Disruption to normal daily circadian rhythms was associated with higher rates of mood disorders such as severe depression and bipolar disorder, according to findings from the largest observational study of circadian rhythms to date, published in the Lancet Psychiatry.
Although previous research has identified associations between disruptions in circadian rhythm and poor mental health, these studies typically had small sample sizes, were based on self-reports, or adjusted for few potential confounders.
This study had a sample size large enough to assess the effect of circadian disruption on mental health disorders and was the first to objectively measure patterns of rest and activity (using accelerometers).
Researchers of this study analyzed activity data from 91,105 participants (aged, 37-73 years) from the UK Biobank general population cohort to obtain the relative amplitude of the study population (a variable to determine the degree to which circadian rhythms of rest-activity cycles is disrupted).
To record their levels of activity, participants wore accelerometers for 7 days between 2013 and 2015. Regression models were used to assess the associations between low relative amplitude and mood disorders, well-being, and cognitive variables. The researchers also adjusted for a wide range of factors including age, sex, lifestyle, education, body mass index, and childhood trauma.
The researchers found that a 1-quintile reduction in relative amplitude was associated with increased risk for lifetime major depressive disorder (odds ratio [OR], 1.06; 95% CI, 1.04-1.08) and lifetime bipolar disorder (OR, 1.11; 95% CI, 1.03-1.20). It was also associated with greater mood instability (OR, 1.02; 95% CI 1.01-1.04), higher neuroticism scores (incident rate ratio, 1.01; 95% CI 1.01-1.02), more subjective loneliness (OR, 1.09; 95% CI, 1.07-1.11), lower happiness (OR, 0.91; 95% CI, 0.90-0.93), lower health satisfaction (OR, 0.90; 95% CI, 0.89-0.91), and slower reaction times (linear regression coefficient, 1.75; 95% CI, 1.05-2.45). These associations were independent of confounders including demographic, lifestyle, education, and overall activity.
“Our findings indicate an association between altered daily circadian rhythms and mood disorders and well-being,” said study author Laura Lyall, PhD, from the University of Glasgow, United Kingdom. “However, these are observational associations and cannot tell us whether mood disorders and reduced well-being cause disturbed rest-activity patterns, or whether disturbed circadian rhythmicity makes people vulnerable to mood disorders and poorer well-being.
“To look at this in more detail, it will be useful for future studies to track participants’ rest-activity patterns over time to see whether disturbed rhythms can predict whether someone is more likely to go on to develop a mood disorder,” she concluded.
- Disruption of the body’s internal clock linked with mood disorders and adverse wellbeing [press release]. The Lancet Psychiatry. Published May 14, 2018. Accessed May 14, 2017.
- Lyall LM, Wyse CA, Graham N, et al. Association of disrupted circadian rhythmicity with mood disorders, subjective wellbeing, and cognitive function: a cross-sectional study of 91 105 participants from the UK Biobank [published online May 15, 2018]. Lancet Psychiatry. doi: 10.1016/S2215-0366(18)30139-1