Why We’re So Emotional When We’re Tired

If you’ve been staying up late, trying to keep up with the holidays, you’re probably feeling pretty cranky and sleep deprived. Snapped at a loved one? Snipped at a coworker? Our fuses run as short as the winter daylight. A new study out of Tel Aviv University has identified exactly why we get so emotional when we have been burning the candle at both ends. The research reveals the changes sleep deprivation can impose on our ability to regulate emotions.

For the study, researchers had participants look at “positively emotional” images (a cat), “negatively emotional images” (a mutilated body), and “neutral images” (a spoon). When the participants had enjoyed a good night’s sleep, they were able to ID the images faster, and their EEG brain mapping showed differing neurological responses. But after a night of sleep deprivation, the participants were less able to tell which images were what type of emotion and their brains showed decreased regulatory processing.

“Prior to our study, it was not clear what was responsible for the emotional impairments triggered by sleep loss,” wrote study leader Professor Taima Hendler, of TAU’s Sagol School of Neuroscience. “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 suddenly everything is important,” she wrote.

In a second part of the study, participants were shown neutral and emotional images while performing a task demanding their attention. After only one night of lack of sleep, participants were distracted by every single image—neutral and emotional—compared with well-rested participants, who were only distracted by the emotional images. “These results reveal that, without sleep, the mere recognition of what is an emotional and what is a neutral event is disrupted. 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,” wrote Professor Hendler.

So if you find yourself on high alert, responding to every input like it’s a big crisis, invest in a little more rest and see how much better you will find yourself coping.