If at night we, for example, hear noise, we usually react to it much more emotionally than during the day. But what is the reason for fearfulness – in the time of day or simply because … it is dark?
Psychologist Yadan Li and her colleagues at Southwestern University in China set out to find out how the night itself as a time of day, and not the darkness associated with it, affects our fears. 128 women (average age 22 years) were invited to participate in the experiment. They were in a windowless room, viewing images and listening to sounds played on a computer. Some pictures were neutral (nature, household items), some scary (spiders, violent scenes), sounds could also be neutral (birdsong, fan noise) and scary (screams).
The women were divided into four groups. Participants from the first group sat at the computer in the morning in bright light, from the second – in the afternoon in the dark, from the third – at night (at eight o’clock in the evening in February) with subdued lights, from the fourth group – at night in the dark.
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Women who participated in the experiment at night were more frightened by the terrible images and sounds – both according to their own assessments and according to the data of sensors that monitored their heartbeat and other changes. At the same time, the level of illumination did not matter. The reaction to neutral pictures and sounds did not differ depending on the time of day.
It seems that increased fearfulness at night depends on the time of day, and not on lighting. Perhaps this phenomenon is due to the rhythms that govern the human sleep-wake cycle. Increased attention to danger depending on the time of day (which is known to the “built-in” biological clock) may well have developed in the process of evolution. However, the influence of cultural factors cannot be ruled out – perhaps we have simply learned to be more careful at night.
It is curious that in previous studies of night terrors, scientists did not separate these two factors from each other: time of day and lighting. Learning about the causes of night terrors can help treat certain disorders such as nighttime panic attacks.
Подробнее см. Y. Li et al. «Night or darkness, which intensifies the feeling of fear?», International Journal of Psychophysiology, July 2015.