American psychologists have found that one sleepless night can significantly increase the level of anxiety. To do this, they conducted an experiment in which they asked volunteers either to stay up all night or to sleep normally and then monitored their brain activity in response to frightening Video. It turned out that increased anxiety after a sleepless night is accompanied by a decrease in medial prefrontal cortex activity and a weakening of communication between it and the parts of the brain, responsible for handling emotions. Reducing anxiety helps to reduce anxiety in a prolonged phase of slow sleep, especially when accompanied by brain activity in the range of 0.5 to 4 Hertz.
One of the most common symptoms of increased anxiety and anxiety disorder is sleep problems. Unlike depressive conditions, which can be accompanied by both insomnia and hypersomnia, anxious people in most cases have a lack of sleep. Also, despite the fact that most often it is anxiety that causes insomnia, and not vice versa, lack of normal sleep can exacerbate the disorder, so it is very important to understand all aspects of this connection, for example, to find the most effective treatment.
Psychologists led by Matthew Walker from the University of California at Berkeley decided to understand the question in more detail. They conducted a series of experiments to test the neural mechanisms involved in the occurrence of anxiety with lack of sleep and to evaluate the role that slow sleep plays in getting rid of the disorder. In addition, the authors studied how sleep dynamics affect the manifestation of anxiety symptoms in a small, long-term study.
The first experiment involved 18 people who during the week had to spend a sleepless night in the laboratory (daily lack of sleep) and their usual night with the usual quantity of sleep – for the latter they were provided with an outpatient polysomnograph. In the morning, the researchers studied brain activity using fMRI: participants were shown several videos that should cause disgust or anxiety. In studying the activity, the researchers focused on areas that are usually associated with anxiety: the islet lobe and amygdala (responsible for processing emotions), as well as the anterior cingulate and prefrontal cortex (taking part in cognitive control). In addition, participants completed a standardized questionnaire to identify anxiety.
With the initially the same level of anxiety after a sleepless night, the participants showed a significant increase (p = 0.008), as well as a significant difference with the level of anxiety after nights with a normal amount of sleep (p = 0.009). When watching the video, the activity of the amygdala and islet lobe increased, and a decrease in the activity of the prefrontal cortex was also observed. The activity of the anterior cingulate cortex did not change significantly. The main effect of lack of sleep on increased anxiety, apparently, was regulated by decreased activity of the prefrontal cortex, which is associated with reduced cognitive control, and increased activity of the zones that are responsible for emotional processing, as well as the violation of the connection between these departments.
To test how the level of anxiety is affected by the peculiarities of sleep, the scientists analyzed its individual phases. It turned out that the long duration of the slow sleep phase was positively affected by the reduction of anxiety, and brain activity in the range of 0.5 to 4 Hertz was associated with it. In addition, in the morning after normal sleep, there was an increased (p = 0.01) activity of the prefrontal cortex, which seems to indicate that sleep in the slow phase restores the activity of this zone, which leads to reduced anxiety. The results of this experiment were then reproduced on another 32 participants – they slept in the laboratory instead of home.
To check if there is a short-term relationship between anxiety and quality of sleep (i.e. if lack of sleep can increase anxiety the next day), scientists conducted an online survey among 280 people: they had to fill out a questionnaire on the quality of their sleep and a questionnaire within four days for symptoms of anxiety. It turned out that the change in the quality and quantity of sleep of the participants is actually associated with the manifestation of anxiety (p = 0.001). At the same time, the amount of sleep separately did not affect this indicator.
The authors of the work, therefore, managed to clarify the mechanism of the effect of lack of sleep on the increase of anxiety. Apparently, because of the sleepless night, the prefrontal cortex begins to work slower, leading to a decrease in cognitive control, and especially control over those departments, that are responsible for emotional processing. The researchers also note the therapeutic effect on the anxiety of the slow sleep phase, which, among other things, helps the prefrontal cortex to restore normal Work.