The people which they are most active in the evening hours they have increased risk of developing anxiety and related disorders as they have stronger emotional responses to stimuli that signal potential threats.
An international research team coordinated by scholars of University of Messina And Bologna showed that the people with an evening chronotype – who are more active in the evening – present impaired fear learning.
The study, published in the Journal of Affective Disordersreveals that those who are more productive in the evening have a greater activation of autonomic nervous system (Sna) in implicit fear learning tasks.
“With the term chronotype refers to differences in performance that each person has in relation to periods of sleep and wakefulness during the 24 hours of the day. We can have a morning chronotype if we prefer to wake up early and perform well in activities that start in the morning, a evening chronotype whether we are more productive at night and prefer to stay up late, or finally intermediateif we adapt easily to the morning and evening schedules,” he explains Carmelo Mario Vicar, director of the laboratory of cognitive and social neurosciences of the University of Messina. “In our study we investigated whether some mechanisms underlying these disorders are altered in people with evening chronotype, and whether they are linked to fear learning”, adds Vicario. The results obtained confirm this: a greater vulnerability to anxiety disorders of people with evening chronotype may be linked to an altered fear acquisition mechanism.
“This study provides new insights into the influence of chronotype on cognitive and affective processes, suggesting that the increased vulnerability of evening chronotype to anxiety and related disorders may be mediated by impaired implicit fear learning,” he explains. Alessio Avenantiprofessor at the ‘Renzo Canestrari’ psychology department of the University of Bologna-Cesena Campus, one of the research coordinators.
“The results obtained have several implications: for example, one could act on the chronotype to reduce anxiety and stress levels, monitoring the effectiveness of the intervention with the virtual reality protocol that we used”. The study participants wore a helmet and were immersed in a reality environment in which they observed visual stimuli that were initially neutral and could predict “the occurrence of a fear-inducing scene”, i.e. a monster that suddenly appeared simulating an aggression against the observer.
The researchers resorted to the classic paradigm of fear conditioning, which derives from the studies of the Nobel Prize winner Ivan Pavlov, through a virtual reality system.
“After this exposure, the neutral stimuli associated with the monster (the conditioned stimuli) acquired an aversive emotional property, inducing an increase in sweating, a physiological index that reflects the activation of the autonomic nervous system associated with fear. In this way we have demonstrated that people with evening chronotype show an increase in the physiological response that reflects fear; effect that does not occur in the control group with intermediate chronotype”.