People who experience clear peaks and dips in energy throughout the day may show higher neuroticism and a stronger tendency toward avoidance behaviour, according to researchers from the University of Warsaw.
The study, published in Scientific Reports, suggests that the distinctness of a person’s circadian rhythm — the degree to which energy and mood fluctuate during the day — may be as important as chronotype (being a morning or evening person) and should be considered in brain research.
“Our circadian clock cyclically determines times for activity and rest,” said Patrycja Ściślewska, a neurobiologist at the Faculty of Biology, University of Warsaw. “While the concept of chronotype is quite well-known and frequently studied, distinctness of the circadian rhythm is a relatively new concept. Distinctness indicates the difference between our best and worst hours of the day. Some of us have very specific times when we feel good and times when we function significantly worse.”
The research team examined 37 healthy adults aged 20–30 to explore how both chronotype and rhythm amplitude affect brain function and responses to rewards and punishments. Participants completed personality questionnaires and then performed a monetary reward-punishment task during functional magnetic resonance imaging (fMRI).
“Our study shows that chronotype is more closely related to how we react to positive stimuli, while amplitude is more related to how we react to negative stimuli,” Ściślewska said.
Higher amplitude — or stronger daily fluctuations in mood and energy — was associated with greater neuroticism and a tendency toward behavioural inhibition. At the neural level, this corresponded to increased activation in the ventral tegmental area during anticipation of punishment and the left occipital pole during negative feedback.
“This means that the greater the differences in well-being between the best and worst moments of the day, the greater the tendency to exhibit neuroticism traits and to inhibit behaviour, which promotes avoidance behaviour,” Ściślewska explained. “For example, if someone anticipates that a given meeting will be unpleasant, they may refrain from attending to avoid this negative experience.”
The authors caution that the findings are correlational. “We don’t know enough about subjective rhythm amplitude yet,” Ściślewska said. “But we hope that in time, based on the interconnected characteristics of the biological clock — amplitude and chronotype — we will be able to predict human behaviour in specific situations.”
The team also released an anonymised dataset — including psychometric data, anatomical brain images, and fMRI recordings — openly via the OpenNeuro.org platform. “We encourage researchers from around the world to use our dataset in their analyses,” Ściślewska added.
Researchers from the Nencki Institute of Experimental Biology of the Polish Academy of Sciences, Jaume I University in Spain, and Northeastern Illinois University in the USA also contributed to the study.
PAP - Science in Poland, Ewelina Krajczyńska-Wujec (PAP)
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