Jennifer Lovejoy, Arivale Chief Science Officer, PhD
[Arivale Hot Topics address health stories currently in the news. The Arivale Clinical Team’s commentary on these news articles is not a review of the scientific evidence, nor an endorsement of a specific study, and is not meant as official medical opinion.]
Your circadian rhythm refers to the internal clock that tells you when to wake up, eat, and sleep. Past research has shown your circadian rhythm is important for optimal mental health and wellbeing, while disruption of this internal clock can be associated with mood disorders, especially major depressive disorder and bipolar disorder.
While studies have demonstrated an association between circadian rhythm disruptions and mental health, these studies have mostly relied on self-report measures to assess disruptions, which might not be an accurate picture of participants’ circadian rhythms.
A new study published May 15 in Lancet Psychiatry and covered by CNN addresses this issue while also finding a link between sticking to a normal circadian rhythm and improvements in mood and cognitive functioning, as well as a decreased likelihood of developing major depressive disorder and bipolar disorder.
Researchers looked at the circadian rhythms of 91,105 people between the ages of 37 and 73 in the UK, measuring their sleep-wake cycles with an accelerometer worn on their wrist for seven days in 2013 or 2014 and their mood and cognitive functioning first between 2006 and 2010 and again with an online mental-health questionnaire in 2016 or 2017.
Researchers found people with a higher level of disruption in their circadian rhythm – defined as increased activity at night and/or decreased activity during the day – were notably more likely to have symptoms shared with major depression disorder and bipolar disorder. They were more likely to have decreased feelings of wellbeing and reduced cognitive functioning. They showed higher neuroticism scores, more subjective loneliness, lower happiness, and lower health satisfaction.
These findings still held after accounting for factors that like education, childhood trauma, and body mass index.
As the CNN article mentions, this study cannot – and does not – claim that disruptions in circadian rhythm cause mental health issues. Since data was collected at single time points, it’s unclear if mental health conditions persisted before the circadian rhythm disruptions. In fact, some mental health data, such as loneliness, was collected prior to accelerometer data.
Furthermore, it might be the case – for at least some individuals – that mental health issues are in fact causing disruptions in circadian rhythm, a point not specifically brought up in the CNN article.
Another limitation of this study, also mentioned by CNN, is that the research was conducted in adults between age 37 and 73, meaning the results may not apply to younger individuals, whose circadian rhythms can be different than those of older adults.
This study suggests that maintaining a regular circadian rhythm may be good for your mental health. A regular circadian rhythm is indicated by increased activity during the day and decreased activity at night.
Making time for physical activity during the day, such as walking during your lunch break, may help promote daytime circadian rhythms. In addition, diet and lifestyle changes, such as limiting caffeine in the afternoon and minimizing screen time before bed, can help promote restful uninterrupted sleep at night.