Researchers have now discovered that lack of sleep also affects visual perception – even after just one night.
In scientific circles, chronic sleep deprivation has been recognized as a health risk for some time now. In recent years though, increasing evidence shows that even an acute sleep deficit can lead to a deterioration in health and performance. In the field of research of visual perception, several studies deal with the potential effects of sleep deprivation. Thus, for example, recognizing facial expressions and spatial perception is impaired even after short-term sleep deprivation. So far unexplored, however, is the question whether the emotional experience of visual stimuli too is being influenced; whether the aesthetic perception is different even in the case of a temporary lack of sleep? Such a cehesion could further suggest that too little sleep literally distorts the way we see the world around us.
Sleep deprivation changes visual perception
A collaboration of researchers from the Swedish Uppsala University and Flinders University in South Australia have now addressed this issue. As the first study of its kind so far, their goal was to investigate whether even one sleepless night had a negative effect on visual perception.
The study’s setting
For the purpose of this two-day study, eleven young, healthy men were assigned to two different test conditions: one group was allowed to sleep as usual during the night between 11:00 pm and 7:00 am while the other group was kept awake in the laboratory. The perception of both test groups was measured the evening before and the next morning. The participants were placed in front of a computer screen in a dark room. They looked at 32 photos in succession – 16 landscapes and 16 close-ups of nature. The subject’s task was to digitally manipulate the displayed blurry images until they appeared natural to them. They should also rate the pictures according to how pleasant they appeared to them.
The study’s result
The result: The first measurement the evening before showed no significant difference between the two test groups. However, the second measurement the following morning showed that the landscapes were perceived as less pleasant after a sleepless night. The blurrier the picture, the more “natural” they were perceived by the test participants who had not slept.
However, since the sleeping situation had no effect on the 16 close-ups, the results cannot be explained by a supposed fatigue of the eye muscles. It is not the mere muscular flaccidity that gives rise to the differences in perception – rather, these arise in the processing of complex content. In addition, a state of mind clouded by lack of sleep seems to distort the aesthetic judgment.
Less pleasure due to lack of sleep
Perception researcher Dr. Karin Nordström comments: “Numerous studies have shown that images of nature usually trigger mainly positive emotions. Thus, a reduced sense of pleasure in visual perception could play a role when it comes to the relationship between long-term sleep deficiency and listless states of mind. A classic example of such conditions would be depression.” From these results one could deduce that persistent sleep deprivation favors depressive moods also because the visual environment is less pleasurable.
An extension of the small-scale pilot study is planned. A larger test group should be selected, this time also with female participants and from different age groups.
Source of picture: deathtothestockphoto