Evening people show enhanced fear acquisition which may cause anxiety

According to study, the higher sensitivity of evening chronotype persons to anxiety and associated problems—those who function better at night or in the early hours of the morning—may be impacted by altered emotional learning.

Are you aware of your chronotype? Chronotypes relate to the variations in performance that each person has in response to the periods of sleep and wakefulness during the 24 hours of the day. They are also known as our circadian preference profiles. There are three types of people: morning types (those who prefer to rise early and perform well in activities that begin in the morning), evening types (those who are more productive at night or in the early hours of the morning and prefer to remain up later), and intermediate types (if we easily adapt to morning and evening schedules).

Because they can shed light on the onset of mental diseases like anxiety and post-traumatic stress disorder (PTSD), circadian rhythms are being investigated more and more.

In order to study the neurocognitive underpinnings of the association between chronotype and fear responses in healthy humans, researchers Chiara Lucifora, Giorgio M. Grasso, Michael A. Nitsche, Giovanni D’Italia, Mauro Sortino, Mohammad A. Salehinejad, Alessandra Falzone, Alessio Avenanti, and Carmelo M. Vicario turned to the traditional Pavlovian paradigm of fear conditioning.

Enhanced fear acquisition in those with evening chronotypes is discussed in the paper. The researchers from Universita Degli Studi di Messina and Universita di Bologna (Italy), Leibniz Research Center for Working Environment and Human Factors (Germany), and Universidad Catolica Del Maule (Chile), describe their “Virtual Reality Fear Conditioning/Extinction Study” in which they used 40 participants recruited from students at the University of Messina, 20 of whom had an evening chronotype and 20 controls.

“To the best of our knowledge, only one study (Pace-Schott et al., 2015) to date explored the role of chronotypes on the fear acquisition and extinction in healthy humans, but did not test intermediate chronotypes, the ideal control group as they are the most frequent chronotype in the population”, explains Carmelo M. Vicario, a researcher supported by the BIAL Foundation.
The findings in the two groups supported earlier research linking the evening chronotype to a higher risk of anxiety disorders and PTSD. The results in the two groups showed a higher fear acquisition response in evening chronotype individuals compared to intermediate chronotype participants.

“This study provides new insights about the influence of circadian rhythms on cognitive and affective processes, suggesting that the higher vulnerability of the evening chronotype to anxiety and related disorders may be mediated by altered fear acquisition,” says Vicario.