May 16 (UPI) -- People who disrupt their body clock -- being active at night or inactive during the day -- have a greater risk of developing mood disorders, according to a study in Britain.
Researchers from the University of Glasgow in Britain found a regular sleep-wake cycle avoids depression, bipolar disorder and other conditions. Their findings were published Tuesday in the journal The Lancet Psychiatry.
Glasgow researchers analyzed data on 91,103 people from Britain between age 37 and 73 from the UK Biobank that was collected between 2013 and 2015. Participants wore accelerometers for seven days to record their activity and answered health questionnaires to assess symptoms of mental disorders and subjective questions on well-being and cognitive function. Mathematical modeling then was used to find a correlation and assess risk.
Researchers report that body clock disruption was associated with mood instability, more subjective loneliness, lower happiness and health satisfaction, and worse cognitive function. And these results held true when adjusting for age, sex, lifestyle, education, body mass index and childhood trauma, the researchers say.
"Our findings indicate an association between altered daily circadian rhythms and mood disorders and well-being," Dr. Laura Lyall, a researcher at the University of Glasgow, said in a press release. "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."
Daily circadian rhythms regulate things such as body temperature and eating habits in almost all organisms. With the brain's internal time-keeping system, it anticipates environmental changes and adapts to the appropriate time of day.
People who were active during the night or inactive during the day were 6 percent to 10 percent more likely to be diagnosed with a mood disorder than those who followed a normal cycle of being active during the day and switching to rest at night.
"While our findings can't tell us about the direction of causality, they reinforce the idea that mood disorders are associated with disturbed circadian rhythms, and we provide evidence that altered rest-activity rhythms are also linked to worse subjective well-being and cognitive ability," Lyall said.
The authors noted that there was time difference between the recording of demographic and lifestyle data of between 2006 and 2010, accelerometry data from 2013 and 2014, and information from the mental health questionnaire from 2016 and 2017.
The authors said expanded research is necessary because while the current study was instructive, 75 percent of mental health disorders start before age 62 -- and the median age of UK Biobank participants is 62.
"Given that most mental health disorders begin during adolescence, more longitudinal studies in younger populations might improve our understanding of causal mechanisms, and help find new ways to predict mood disorders and fine-tune treatments," the authors wrote in the study.