(photo credit: INGIMAGE)
Getting too little sleep at night harms the brain’s ability to regulate emotions and cope with anxiety, according to a Tel Aviv University study recently published in Journal of Neuroscience.
The research, conducted on 18 adults who were kept awake all night, was led by Prof. Talma Hendler of TAU’s Sagol School of Neuroscience at the Sackler Faculty of Medicine and School of Psychological Sciences and conducted by graduate student Eti Ben-Simon at the Center for Brain Functions at Tel Aviv Sourasky Medical Center.
Since many Israelis – like most Americans and other Westerners – get too little sleep, this finding is bad news.
The team identified the neurological mechanism responsible for disturbed regulation of emotion and increased anxiety in the subjects after only one sleep deprived night. They discovered the changes that lack of sleep can impose on our ability to regulate emotions and allocate brain resources for cognitive processing.
“Prior to our study, it was not clear what was responsible for the emotional impairments triggered by sleep loss,” said Hendler.
“We assumed that sleep loss would intensify the processing of emotional images and thus impede brain capacity for executive functions.
We were actually surprised to find that it significantly impacts the processing of both neutral and emotionally-charged images. It turns out we lose our neutrality. The ability of the brain to tell what’s important is compromised.
It’s as if everything is suddenly important,” she said.
The first night of the experiment, they let the group sleep well. The next night, they kept the 18 people awake all night to take two rounds of tests while undergoing brain mapping (functional MRI or fMRI and/or an electroencephalogram or EEG).
One of the tests required participants to describe in which direction small yellow dots moved over distracting images. These images were “positively emotional” (a cat), “negatively emotional” (a mutilated body), or “neutral” (a spoon).
When participants had a good night’s rest, they identified the direction of the dots hovering over the neutral images faster and more accurately, and their EEG pointed to differing neurological responses to neutral and emotional distractors. When sleep deprived, however, participants performed badly in the cases of both the neutral and the emotional images, and their electrical brain responses did not reflect a highly different response to the different emotional images.
This pointed to decreased regulatory processing.
“It could be that sleep deprivation universally impairs judgment, but it is more likely that a lack of sleep causes neutral images to provoke an emotional response,” said Ben-Simon.
The researchers conducted a second experiment testing concentration levels in which participants were shown neutral and emotional images when performing an attention demanding task – the depression of a key or button at certain moments – while being forced to ignore distracting background pictures with emotional or neutral content. The subjects performed the task inside an fMRI scanner so that while completing the cognitive task, researchers could measure activity levels in different parts of the brain.
The team found that after only one night of being awake, the participants were distracted by every single image (neutral and emotional), while well-rested participants were only distracted by emotional images. The effect was indicated by activity change in the amygdala, a major limbic node responsible for emotional processing in the brain.
These results reveal that, without sleep, the mere recognition of what is an emotional and what is a neutral event is disrupted, Hendler said. “We may experience similar emotional provocations from all incoming events, even neutral ones, and lose our ability to sort out more or less important information. This can lead to biased cognitive processing and poor judgment as well as anxiety.”
The new findings emphasize the vital role sleep plays in maintaining good emotional balance and for promoting mental health.
The researchers are now examining how novel methods for sleep intervention (mostly focusing on rapid-eye-movement sleep) may help reduce the emotional dysregulation seen in anxiety, depression and traumatic stress disorders.