I don’t need to tell you that lack of sleep makes you testy, irritable, and short-tempered. We all know, through experience, how sleep deprivation puts us on a short fuse.
Still, like with the cognitive impacts of sleep deprivation, most of my patients don’t realize how deeply sleep deprivation—especially when chronic—hurts their emotional well being, affecting their mental health, their outlook and performance, and their relationships.
Sleep Deprivation Makes You More Emotionally Reactive
Whether snapping at a co-worker, getting a fight with your partner, or losing your cool with your kids, not getting enough sleep increases the likelihood your emotional responses will be more impulsive and intense. None of these situations are fun, or contribute to healthier, happier relationships. But emotional reactivity goes beyond being cranky. That same hair trigger that makes us irritable with the people around us can be exhausting and draining, leaving us feeling at the mercy of our feelings and critical of ourselves for not being more adept at managing our own emotions.
We’re still learning about the ways that sleep and emotion are connected. But we do know some pretty interesting things about how sleep deprivation affects the complex emotional centers of the brain, making us more likely to overreact, or lash out in anger and frustration. Even a single night of sleep deprivation sets us up to react more strongly and impulsively to negative or unpleasant situations, according to research.
Research shows sleep deprivation increases activity in the emotional rapid response center of the brain—an area known as the amygdala. This part of the brain controls many of our immediate emotional reactions. When short on sleep, the amygdala goes into overdrive, causing us to be more intensely reactive to situations. Interestingly, it’s not only our negative emotions, like anger and fear, that get a heightened response. Studies show that when sleep deprived, we’re more reactive across the whole spectrum of our emotions, positive and negative.
At the same time the amygdala is fired up, lack of sleep also hampers the communication between the amygdala and another area of the brain involved in emotional regulation—the prefrontal cortex. This part of the brain handles a lot of complex tasks, and when you don’t get enough sleep, it can’t do its job as well. As a result, you become more impulsive and less thoughtful in your emotional responses.
We all go through emotionally-charged experiences, large and small, every day and throughout the course of our lives. Those experiences get stored in the brain as memories—and sleep plays an important role in processing those memories. REM sleep in particular appears to be especially important to processing painful and difficult memories. This process helps ease the emotional sting these memories can have. It also helps your emotional mind return to a less-charged, more-neutral state. This nightly emotional re-set is important for your ongoing mental health.
REM sleep occurs in a series of episodes over the course of a night’s sleep. As the night progresses, episodes of REM get longer, with most REM occurring in the last third of the night. When your sleep is shortchanged, your brain doesn’t get the benefit of this restorative work, and your emotional life can suffer.
You Have a More Negative Outlook
Knowing how our brain’s emotional centers are affected by lack of sleep, it’s not difficult to imagine how sleep deprivation can contribute to a more negative mindset. Sleeping poorly makes us focus more on the negative, and increases what psychologists call repetitive negative thinking: that’s when your mind is stuck in a negative place, going over the same frustrated thoughts again and again. Repetitive negative thoughts are intrusive, difficult to control, and can have a major impact on how you feel and function. They’re also linked to the development of the mood disorders depression and anxiety.
Scientists also found that the greater the sleep deprivation, the more difficult it was for people to turn their minds away from ruminating on negative thoughts, feelings, and experiences. No one would ever choose to have a mind that’s trapped in a cycle of negative thinking. Unfortunately, when you’re chronically short on sleep, that’s what happens—and it can be a difficult cycle to break.
You Worry More About the Future
Sleep deprivation exacerbates emotional reactivity and fearful responses, and creates an often-intractable negative outlook. It also makes us worry more. Recent research shows that when we’re sleep deprived, we worry more about the future—especially if we’re prone to worry in general.
Scientists at University of California Berkeley found sleep deprivation increases anticipatory anxiety—that’s worry about what’s to come. We’ve known for a long time that sleep deprivation increases anxiety, and contributes to anxiety disorders. Their study provides some important new insight into more precisely how lack of sleep aggravates the brain’s worry response.
Brain activity in response to the anticipatory signal was much higher when the participants were sleep deprived than when they were well rested. Again, it was the emotional control centers of the brain that were activated by lack of sleep and contributed to increased anxiety about the future.
Sleep deprivation triggered more anticipatory anxiety in people who were already prone to be worriers, the scientists found. If you tend to worry, getting plenty of rest is especially critical to maintaining a healthy emotional balance and avoiding the development of chronic anxiety.
You Feel Less Connected to Your Partner
Sleep deprivation doesn’t only affect our individual emotional well being. It also undermines healthy, satisfying relationships. I’ve talked about how sleep deprivation can sink a healthy sex life. It also can interfere with other forms of intimacy between partners.
Of course, being emotionally more reactive and focused on the negative isn’t likely to improve anyone’s relationship. But sleep deprivation also directly affects how we perceive and treat our partners.
One study found that lack of sleep diminishes gratitude for our romantic partners. Researchers found that it only took one person in the relationship to be short on sleep for both partners to feel a diminished sense of gratitude toward the other. That’s right: your partner’s poor sleep can make you less appreciative of them, even if you aren’t lacking sleep yourself.
Sleep deprivation also diminishes our capacity for empathy, an emotional skill that’s critical to healthy relationships. Empathy is the ability to understand another person’s feelings, thoughts, and experiences. I tell my patients to think of it as the experience of truly walking in another person’s shoes.
When sleep deprived, we’recalso less able to demonstrate empathy for others. That means we’re less able to see things from another person’s point of view, less able to recognize and imagine their feelings. This aligns with other research showing that sleep deprivation impairs our ability to accurately recognize emotions in other people.
These skills of self-awareness, appreciation for others, and empathy are essential parts of our emotional intelligence—and sleep deprivation impairs them, often weakening our bonds of trust and communication in the relationships that are most important to us. Studies show couples who are sleep deprived fight more and resolve conflicts less successfully than well rested partners. And it only takes one person in a couple who is short on sleep to increase conflicts.
Women and Men Experience Sleep Deprived Emotions Differently
As with other aspects of sleep deprivation, men and women appear to experience some of the emotional impact of poor sleep differently. I led a study a few years ago that investigated how much sleep men and women need. Our study found women experience more anger, more hostility, and more depression first thing in the morning than men do. We know that overall, women’s brains expend more energy than men’s do. Most scientists chalk this up to women’s ability to multitask. That additional energy expenditure means women need more sleep, to restore full, healthy function to their brains. When they don’t get the full amount of restorative sleep they need, emotional difficulties can arise. They arise for men too—but women’s may occur more quickly or more often, because of women’s particular sleep needs.
Sleep’s relationship to our emotional lives is another important example of why sleep is a necessity, not a luxury. Your mental and emotional health—and your relationships with others, in your personal and professional life—depend on you getting plenty of high-quality rest.
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