Study Links Disrupted Circadian Rhythms to Mood Disorders
Importance of Circadian and Sleep Rhythms
A recent study explored the relationship between disrupted circadian and sleep rhythms and the increased risk of mood disorders. Sleep and circadian rhythms are crucial elements of overall health and play a vital role in maintaining a balanced lifestyle. Circadian rhythms are defined as the physiological and behavioral changes that occur within a 24-hour cycle. Research indicates that disturbances in these rhythms can adversely affect mood, leading to conditions such as major depressive disorder and bipolar disorder.
Previous Research Limitations
Many earlier studies examining circadian rhythms and mood disorders involved a limited number of participants and primarily relied on subjective assessments of circadian functions. In contrast, the recent study utilized data from over 90,000 individuals from the UK Biobank. This marks the first large-scale research employing objective measurements of circadian rhythms to investigate their connections to well-being, personality, mental health, and cognitive outcomes.
Study Overview
Conducted in the United Kingdom and published in The Lancet Psychiatry in May 2018, the study recruited UK residents aged 37-73 years into the UK Biobank general population cohort between 2006 and 2010. Participants were asked to wear accelerometers to track physical activity. Researchers collected data on various demographic factors, including age, sex, gender, ethnic background, education level, and lifestyle choices. A mental health questionnaire categorized participants based on their experiences with childhood trauma and assessed their histories of major depressive disorder and bipolar disorder. Additionally, several brief cognitive tests were administered.
Key Findings
The study revealed significant insights regarding the connection between circadian rhythms and mood disorders. Researchers examined the fluctuations of circadian rhythms, which influence feelings of wakefulness and sleepiness throughout the day. They discovered that lower rhythmic amplitude—characterized by smaller differences in activity between periods of activity and rest—was linked to impaired judgment, mood disorders, and decreased overall well-being. Specifically, lower circadian amplitudes correlated with increased odds of lifetime depressive disorders and mood disorders, as well as heightened feelings of loneliness, mood instability, reduced self-rated happiness, slower reaction times, and lower health satisfaction.
Impact on Cognitive Functioning
Prior research on shift workers has shown that sleep deprivation can lead to deficits in memory, attention, and reaction times. The findings of this study support the notion that disruptions in circadian rhythms negatively affect neurocognitive functioning. However, as this research is cross-sectional, it does not establish causality between circadian disruption and diminished functioning or mental health outcomes.
Future Research Directions
This study underscores the potential of circadian amplitude measurements in predicting mood disorders. Further research utilizing accelerometer-derived measurements could provide deeper insights into the adverse effects of disrupted circadian rhythms on mental health and overall well-being.
Reference
Lyall, L. M., Wyse, C. A., Graham, N., Ferguson, A., Lyall, D. M., Cullen, B., … & Strawbridge, R. J. (2018). 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. The Lancet Psychiatry.