Lower relative amplitude was also found to be reliably associated with greater mood instability, higher neuroticism scores, more subjective loneliness, lower happiness and health satisfaction, and slower reaction time (an indirect measure of cognitive function).
The brain's hard-wired circadian timekeeper governs day-night cycles, influencing sleep patterns, the release of hormones and even body temperature.
The circadian rhythm disruptions were defined as an increased nighttime activity, decreased daytime activity, or both at the same time. They occur in plants, animals and throughout biology, and are fundamental for maintaining health in humans, particularly mental health and wellbeing.
"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.
Researchers from the University of Glasgow in the United Kingdom noted that a regular sleep-wake cycle is "crucial" for mental health and well-being, as they associate certain forms of disruption with mood disorders such as depression and bipolar disorder.
Earlier research had suggested that disrupting these rhythms can adversely affect mental health, but was inconclusive: most data was self-reported, participant groups were small, and potentially data-skewing factors were not ruled out.
A newly published study, which examined more than 91,000 people, linked a disrupted internal clock (being active at night or inactive during the day) with the development of mood disorders. "However, these are observational associations and can not 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". Shifts in energy levels and sleep disturbances are common during clinical depression and episodes of bipolar disorder.
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).
"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 wellbeing and cognitive ability", said Dr Lyall.
"This is important globally because more and more people are living in urban environments that are known to increase the risk of circadian disruption and, by extension, adverse mental health outcomes". Note: material may have been edited for length and content. M., Cullen, B.,. & Strawbridge, R. J.
Boston Celtics overcome another huge night from LeBron James
Boston had no such problem with scoring distribution - with all five starters plus Marcus Smart scoring in double-figures. "On the third quarter - where the Cavs were outscored 36-22 - James explained: "[It got away from us] With turnovers.