Do you want to have more success, increase your happiness, or get more things done? Then get up early!
Do these suggestions sound familiar to you? Take my advice and don’t follow them. Cutting down on morning sleep is exactly what you don’t need if you want to become more productive.
Sleep is imperative for the functioning of your memory
It always amazes me how often we still hear the myth that you’ll be more productive if you have more hours each day. Unfortunately, the belief that sleep is an annoying necessity that should be kept at a strict minimum to enhance productivity is still firmly anchored in our society. From childhood, we are forced to get up early. School start times and work schedules are strongly biased toward early mornings that leaves many of us with insufficient sleep. What is often overlooked here is that it is precisely the last 1 to 2 hours of your sleep that have a significant impact on your health and memory.
Everyone knows that healthy sleep and its rejuvenating effect is essential to maintain your mental and physical health. But sleep is also imperative for the functioning of your memory and successful learning. Adequate sleep enables your memory to form new pathways and to process information that can be retrieved later. The memory aiding effects of sleep occur both before learning, to prepare your brain for making new memories, and after learning, to strengthen new memories and prevent forgetting.
Memory and the different sleep stages
All stages of your sleep contribute to overnight memory processes, but their roles differ. Before we go into the details of the fascinating interplay between sleep and memory consolidation a quick recap of the different sleep stages.
Our sleep consists of the two basic types, rapid-eye-movement (REM) sleep and non-rapid-eye-movement (NREM) sleep. During a typical night, you cycle through all stages of NREM and REM sleep several times. Each cycle takes about 90 min, during which NREM sleep and REM sleep alternate. NREM lasts for longer periods in the first half of the night while REM periods increase toward morning.
NREM sleep can be further subdivided into 1 to 3 sleep stages, which resemble the depth of sleep. NREM sleep stage 3 is also known as deep sleep or slow wave sleep because it shows high slow wave activity. During that stage your responsiveness to external stimuli is minimal.
NREM sleep stage 2 is determined by the occurrence of sleep spindles, sudden bursts of brainwaves which can easily be identified on an EEG reading. As you will learn this stage is highly important for information processing in your brain.
NREM sleep stage 1 is a transitory stage making up less than 10% of a night’s sleep.
REM sleep is the stage in which most of your dreaming happens, although some can also occur in NREM sleep. Your eyes move rapidly from side to side behind closed eyelids, and your arm and leg muscles become temporarily paralyzed, which prevents you from acting out your dreams.
Regarding memory consolidation, no one stage of sleep accomplishes all, meaning that no one type of sleep is more essential than another. Light NREM sleep, deep NREM sleep, and REM sleep all offer different brain benefits at different times of the night. Thus, losing out on any one of these types of sleep will weaken your brain function.
The importance of stage 2 NREM sleep and sleep spindles for your memory
Stage 2 NREM sleep is crucial for a successful memory transfer and consolidation process because that is when most of your sleep spindles occur. Sleep spindles are bursts of electrical activity in your brain, which are crucial for the process to maintain, strengthen and modify memories. Once your memories undergo the process of consolidation, they become part of your long-term memory and can be seen as stable. That’s why getting enough NREM is so important when you are learning: it protects the newly acquired information and makes you immune against forgetting.
The more sleep spindles you obtain during your sleep, the higher the restoration of your learning when you wake up. Interestingly the concentration of these sleep spindles is the highest in the late-morning hours of NREM sleep, meaning that is also when your learning benefits are greatest. If you wake up too early and skip the last two hours of your sleep, you are depriving your brain of this unique memory restoration opportunity.
Deep, slow-wave sleep and memory consolidation
When you try to memorize a ten-digit telephone number or someone’s name, this new information is stored in your short-term memory, also known as working memory. However, the capacity of your short-term memory is very limited, and it offers only temporary storage. What seems to be a disadvantage is also a way of your brain to protect you from overloading with useless information. Information you don’t repeat because you consider them unimportant, won’t reach your long-term memory and you will forget them very quickly.
However, newly acquired information you want to memorize needs to be shifted into the long-term storage of your brain. This frees up space in your short-term memory stores and gives you the ability for new learning.
This is where NREM sleep stage 3 comes into play. Although during this stage, your brain is completely decoupled from sensory input, it remains highly active and performs essential learning-related activities. New information, which you acquired during wakefulness, is progressively transferred from fast-learning temporary to slow-learning long-term memory. Responsible are the slow brainwaves of deep NREM sleep which serve as a courier, transporting memory packets from a temporary storage hold to a more secure, permanent home.
Deep sleep is therefore crucial for a smooth interplay between the hippocampus as your short-term memory storage and the cortex as your long-term memory storage. The hippocampus initially acts as a hub. By binding and repeatedly reactivating the memory, it serves as a trainer for the long-term store of the cortex. The cortical connections become stronger and eventually act independently of the hippocampus.
Sleep is your memory backup system
And there is more: The nightly memory transfer cycle also helps to rescue those memories that were lost soon after learning. In other words, you regain access to memories that you could not retrieve before going to bed. Like an overnight computer backup system, your sleep serves as a reliable memory recovery solution. An “aha” effect, the sudden moment of comprehension and recollection, which we all experience from time to time is the exact result of that: once unavailable memories are suddenly popping up in our mind and starting to make sense, only because we had a good night’s sleep.
Why you shouldn’t forget to dream while learning
All that we have covered so far relates mainly to your declarative memory, meaning fact-based, textbook-like information processing like the recollection of phone numbers, a person’s name or dates for a history class. For this type of memory, deep slow-wave NREM sleep which occurs mostly during the first half of the night is making the biggest contribution to your memory retention capabilities.
However, there is another very important memory type, that of nondeclarative memories also called skill memory. A skill memory refers to a task that you do without consciously thinking about it, such as driving a car or playing the guitar. You don’t master those type of skills by merely reading a textbook on how to ride a bike or how to play the guitar. The only way to learn these activities is by repeated practice.
Let’s say you want to learn how to play the guitar. Every day you pick up your guitar and across a certain period you gradually improve your skills. However, it is not only the training during wakefulness which leads to mastery; equally important is your sleep, specifically REM-rich dream sleep during which your brain improves your skill memories. In his excellent book Why We Sleep, Mathew Walker puts it in a nutshell by noting: “Practice does not make perfect. It is practice, followed by a night of sleep, that leads to perfection.”
Most of your REM sleep occurs during the last two hours of your night, precisely those hours you may eliminate from your sleep to get an early start of the day.
The importance of naps for efficient learning
Take naps: Over the day, your encoding ability, meaning your capability to learn and adapt from previous experiences, deteriorates. Taking naps help to maintain your performance. Longer naps that contain sufficient numbers of sleep spindles are said to offer significant skill memory improvement. But even short naps after intense periods of learning support memory consolidation and subsequent learning.
However, keep in mind that naps cannot replace a good night’s sleep. Some types of memories definitely require the cyclic occurrence of all sleep stages you only get during a whole night of sleep. Consider napping rather as an addition to your nocturnal sleep.
Sleep is not idle time but an active state during which the brain performs essential memory consolidation processes. It is during your sleep before and after learning when you undergo critical memory strengthening and retaining processes. New information acquired during the day is safely stored away. At the same time, your memory can prepare for the demands of the next day offering you the capacity for new learning.
That is why you shouldn’t see getting a full night rest with sufficient sleep in the morning hours as a luxury. Instead, start recognizing sleep as a worthy and skillful companion that helps your brain to work at its best.