I have been interested in new learning techniques for quite some time now, and I’d like to share my most enjoyable attempt on that quest: taking better care of my sleep.
I have always believed that my habit of sleeping long was a bad one. Instead, I was intrigued by stories of famous and successful people, who optimized their sleeping time to be more productive during the day. Now, I am certain that most of these stories are only legends, neither based on reality nor helpful inspirations for my own sleeping habits. In case you are still interested in sleeping myths of famous personalities such as Donald Trump or Albert Einstein, check out the best-of infographic at DisturbMeNot.
The starting point of my mind change has been the book Why We Sleep by Matthew Walker. He is a professor of neuroscience and psychology at UC Berkeley, contributing to highest-profile research on the impact of sleep on human health. Walker likes to compare sleep to a revolutionary drug that makes us feel happier, smarter, and healthier. If such a drug existed, would we not all want to take it? What particularly struck me as a student was the impact sleep has on our cognitive performance. Have the painful late-night learning sessions before an exam been useless, in fact, counterproductive for me?
Sleep is more than the absence of wakefulness
Humans do not just sleep but cycle through two completely different types of sleep. These types are called rapid eye movement (REM) and non-rapid eye movement (NREM) sleep. The brain activity of REM sleep is almost identical to the state when we are awake and marks the time during sleep, in which we are dreaming. It is also associated with paralysis of muscle systems in the body and rapid movements of the eyes (that is where the name comes from).
NREM sleep is subdivided into four separate stages depending on their depth. The deepest sleep we experience is stage 4 NREM sleep, meaning it is the time in which it is most difficult to wake us up. Below is a graph that illustrates the interplay between REM and NREM sleep throughout a typical night between 11 pm to 7 am:
The graph shows a continuous alternation between REM and NREM sleep in approximately ninety-minute cycles. However, the ratio of NREM to REM sleep within each cycle changes dramatically across the night. In the first half, the vast majority of our sleep is consumed by deep NREM and very little REM sleep. As we transition through into the second half of the night, the ratio shifts, with most of the time dominated by REM sleep, and little, if any, deep NREM sleep. This pattern suggests that going to bed either very late or waking up very early deprives us of one stage of sleep disproportionally, elevating the harm of unnatural sleeping habits.
Sleep increases our ability to memorize content
In his book, Walker lays out plenty of benefits related to sufficient sleep, including the positive effects for memorization of fact-based, textbook-like content:
- Sleep before learning refreshes our ability to make new memories
- Sleep after learning saves newly acquired memories, an operation called consolidation
The memory refreshment before studying is related to lighter, stage 2 NREM sleep with short, powerful bursts of electrical activity called sleep spindles (see graph below).
The more sleep spindles we obtain during sleep, the greater is the refreshing effect for our short term storage in the brain. The reason behind it is that during stage 2 NREM sleep, electrical current is pulsating back and forth between a temporary storage (the hippocampus) and a long-term one (the cortex). In doing so, sleep delightfully clears out the hippocampus, leaving this short-term information repository with plentiful free space. We awake with a refreshed capacity to absorb new information within the hippocampus, having relocated yesterday’s experiences to a more permanent depot. Note that sleep is equally relevant after a learning session. Particularly early-night sleep with abundant deep NREM facilitates memory retention. The more deep NREM sleep we get, the more information we remember the next day.
Have a tough problem? Sleep on it!
In the online course Learning How To Learn on Coursera, instructor Dr Oakley explains that toxic products aggregate in our brain and sleep washes these toxins out. But sleep does even much more than that. It’s actually a crucial part of the learning process of complex problems. During sleep, we continue to work on the concepts we were just learning about. Our brain strengthens the neural patterns to contextualize the content and get back to it the upcoming day. Plenty of anecdotal evidence suggests that sleep is remarkably helpful to figure out challenging problems that we could not solve during the day in our focused mode:
“It’s as if the complete deactivation of the conscious you in the prefrontal cortex at the forefront of your brain helps other areas of your brain start talking more easily to one another allowing them to put together the neural solution to your learning task while you’re sleeping.”
Dr Oakley, Instructor of Learning How to Learn
For me, sleep always had a bad reputation. I associated sleeping long with laziness and waste of time. Whenever I woke up late or slept too long, I felt guilty that I was not doing something else instead. “Sleep is for the weak” was the motto I believed in. Today, I track my time in bed using the app Sleep Cycle, and I feel full of drive when I wake up, seeing that I’ve had a solid 9-hour rest. Sleep can enhance our memory and ability to solve complex problems. Contrarily, lack of sleep can hinder us unfold our full potential in stressful situations such as during exams. Therefore, I take better care of my sleep, which I also enjoy very much. Now, time for a little nap?
