We all know that poor sleep can affect our mood. Not getting enough sleep often leaves us feeling cranky, or irritable, or just unable to feel positive.
But why exactly are our emotions so affected by lack of sleep?
This is a complex topic, and explaining everything all at once would be overwhelming. Instead, I will focus on one aspect of how sleep deprivation affects our emotions. Additionally, I will briefly explain why trying to catch-up on sleep may not be the best idea.
Summary: Partial sleep deprivation (also known as sleep debt) increases negative emotions, including fear, anxiety, and anger. Research has shown that achieving consistent, quality sleep is more beneficial than trying to make-up for lost sleep. Studies have also found decreased communication between parts of the brain when sleep deprived, which increases our negative emotions.
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How Much Sleep Do I Need?
Let’s begin today’s discussion by quickly addressing the most obvious of all sleep-related questions: how much sleep do I need?
Luckily, we have an easy answer.
In 2015, the American Academy of Sleep Medicine and the Sleep Research Society released a joint statement on the recommended amount of sleep for a healthy adult. They recommended that adults should sleep 7 or more hours on a regular basis.
Their recommendation included a few further explanations and clarifications. First, they reiterated that sleeping less than 7 hours a night on a regular basis can negatively affect your health. These negative health outcomes include weight gain, increased chance of diabetes and high blood pressure, impaired motor skills, reduced immune capabilities, and increased pain.
Second, they recommended that young adults sleep more than 9 hours on a regular basis. This recommendation was also made for those recovering from sleep debt (which we’ll discuss in a little bit), as well as those fighting an illness.
Finally, they noted it is still uncertain whether sleeping more than 9 hours on a regular basis could have negative health risks in healthy adults.
So to generalize their statement: healthy adults should sleep 7-9 hours on a regular basis.
What is Sleep Debt?
I remember hearing the term “sleep debt” when I was in middle school. And I even remember my 7th grade science teacher saying, “once you have sleep debt, you can never make-up for it.”
The official term for sleep debt is partial sleep deprivation. Partial sleep deprivation refers to not getting enough sleep over a period of at least a few days. So, like real-life debt, sleep debt compounds over time.
Let’s say over the course of a five-day work week you consistently sleep 5 hours a night. And let’s say you need the minimum amount of recommended sleep, which is 7 hours a night. Over those five days you have accumulated a sleep debt of 10 hours.
But can you pay back your sleep debt by sleeping extra on the weekend? Not necessarily.
On the one hand, the joint statement above does recommend that sleeping more than 9 hours consistently could help you recover from sleep debt. But keep in mind that this recommendation is calling for consistency (in other words, you should sleep more than 9 hours daily, not just on the weekend).
On the other hand, research has shown that extending your sleep on the weekend is not a quick fix for chronic lack of sleep. Making-up for your sleep debt on paper doesn’t actually improve your health. In fact, extending your sleep on the weekend has been shown to promote additional negative side effects.
These negative side effects include increased calorie intake, weight gain, and changes in how the body uses insulin. So sleeping extra on the weekend to catch-up on sleep leaves you at a higher risk for obesity and diabetes. Similarly, if you are struggling to lose weight, sleeping extra on the weekend may be preventing you from achieving your weight loss goals.
How Sleep Deprivation Affects Your Emotions
This is a dense topic, and I am only focusing on one specific aspect of how sleep deprivation affects emotions. Further discussions of this topic would be well-suited for additional articles.
I discovered a 2013 sleep study from Japan that attempted to find a neurological connection between sleep deprivation and negative emotions. This was, surprisingly, the first study to attempt to answer this question.
(Keep in mind that this study is already seven years old by the time I’m writing this. Should new studies be done, I will update this information if needed.)
This study’s key finding is that people who are sleep deprived have increased activity in their left amygdala, which is responsible for processing negative emotions. The amygdala are a pair of cell clusters responsible for processing emotions. This also occurs due to a lack of communication between the amygdala and the anterior cingulate cortex. The anterior cingulate cortex is a part of the brain that helps in decision-making, as well as controlling emotions.
The participants in this study were partially sleep deprived and showed pictures indicating a range of emotions. The participants had increased sensitivity to negative emotions, particularly fear. Additionally, positive emotions had no change in response when sleep deprived.
What we, and the researchers, can conclude from this finding is that we are more likely to have a heightened response to negative emotions when sleep deprived. In other words, subtle expressions of negative emotions are more likely to be overblown or taken out of context when we are sleep deprived.
Finally, our ability to subjectively, and accurately, process negative emotions is significantly diminished when sleep deprived.
It’s fascinating to learn that our bad mood, or irritability, from poor sleep is due to poor communication within our brain.
I personally like knowing the science behind all of these topics because I enjoy understanding how things work. And by understanding how our body works when sleep deprived, it gives us motivation to improve our sleep, which in turn will improve our overall health.
If you have other sleep-related questions, or questions on the science of sleep, let me know in the comments. We are building a community, and I want to address what the community wants to learn.
- Weekend catch-up sleep won’t fix the effects of sleep deprivation on your waistline
- The Impact of Sleep Debt on Excess Adiposity and Insulin Sensitivity in Patients with Early Type 2 Diabetes Mellitus
- Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society
- Sleep Debt Elicits Negative Emotional Reaction through Diminished Amygdala-Anterior Cingulate Functional Connectivity
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