You might wonder what emotion has to do with learning, and why I am writing a blog about sleep and emotion. If you think about it, though, how you to react challenging situations - the emotions you feel, and the cognitions, physiology, and behaviors that accompany them - can have a profound impact on how you learn. Indeed, emotional reactivity can have a profound impact in multiple domains, but in this blog we will focus on its impact on learning.
Modern neuroscience is not necessary to understand that sleep is fundamentally important. However, it increasingly allows us to understand why that is the case. Andrea Goldstein and Matt Walker reviewed the literature on sleep and emotion and make a compelling case for the causal role of sleep in optimal affective brain function. For our purposes, I want to focus on the overarching theme of how sleep deprivation diminishes effective emotional reactivity.
When people are sleep deprived for even one night, functional brain differences emerge. The limbic system, often colloquially thought of as the brain's "emotional center," is more reactive to both positive and negative emotional stimuli, while the prefrontal cortex - the part of the brain that monitors activity in the limbic system and helps us decide how to respond - is less active. Taken together, this essentially equates to a double whammy: emotional reactivity increases, while our ability to control it simultaneously diminishes - a dangerous combination!
In anxiety-provoking situations (e.g. test taking), this results in higher levels of anxiety and a reduced ability to calm ourselves down and focus on the task at hand. Moreover, this means we are less likely to effectively distinguish between aspects of the situation that should not be anxiety-provoking (e.g. questions that we are confident about) from those that are (e.g. questions we are not confident about). The anxiety becomes generalized to the situation, and our ability to respond logically is significantly impaired.
Furthermore, sleep deprivation's effects are not limited to negative emotional stimuli. When sleep deprived, we are also more likely to overvalue rewards, and undervalue losses. Thus, if you are sleep deprived and faced with the decision of going out with your friends or spending more time studying for an upcoming exam, you are likely to overvalue the rewards of the former and undervalue the loss of additional improvement from the latter. (And interesting side note: you are also more likely to prefer higher-calorie foods and to exhibit a greater tendency to overeat.)
After a restful night, however, the balance between the top-down cognitive processes carried out by the prefrontal cortex and the bottom-up emotional reactivity of the limbic system is restored, making us less likely to mistake noise for signal, and enhancing our ability to plan and make prudent decisions. This is not mere conjecture - it is a physiological fact, as Goldstein and Walker detail in their paper (which I strongly encourage you to read as I've omitted many of the interesting details for the sake of brevity).
So not only will your memory improve if you get enough sleep, your ability to manage your emotions will too. Thus, getting enough sleep is one of the simplest things you can do to make sure you are able to do your best.