This article will share some insights from studies on sleep, performance and memory. These insights may be helpful by enhancing your sleeping habit, which in turn will provide you with increased cognitive performance.
"I do not think there is any thrill that can go through the human heart like that felt by the inventor as he sees some creation of the brain unfolding to success ... Such emotions make a man forget food, sleep, friends, love, everything," - Nicola Tesla
Sleep is a reversible behavioural state of perceptual disengagement from and unresponsiveness to the environment (Carskadon & Dement in Principles and Practice of Sleep Medicine 2005; p.13). Sleep is important at both a cell and network level in terms of repair and maintenance, endocrine function, energy conservation, environmental and brain adaptation, and in learning (Mignot, PLoS Biology, 2008; 6: 661). Other theories relating to the role of sleep involve information processing (memory improves following sleep) and ongoing plasticity of the brain. Gene expression also appears to be altered with sleep. Whatever the true role of sleep it needs to be valued and adequate time set aside for this very important and safety promoting evolutionary state.
The importance of sleep is thus clear from the evolutionary perspective. Most animals have evolved in such a way that they spend considerable periods of time sleeping, despite sleep making us vulnerable (e.g. to attack from predators). The functions of sleep, that is, how sleep functions to support other bodily processes, are still uncertain. However, it is known that REM and non-REM sleep perform different functions, and biochemical, physiological, neurological and psychological process occur differently when an individual sleeps compared to when they are awake.
Now before we proceed you could ask yourself what REM exactly stands for, REM is an acronym for Rapid Eye Movement, and is a phase in our sleep cycle (which will be described next).
Feeling refreshed on awakening does not depend on the amount of sleep someone gets, rather, the amount of sleep cycles that person completed. 9 hours, is the average time an adult spends sleeping each day. Infants average 13 to 15 hours of sleep, while senior adults need only 6 hours or less. Studies have shown mature adults will sleep 10 hours on average when all cues of time are removed. Under the same circumstances apes appear to follow suit. As a sleep cycle takes 90 minutes on average, adults tend to feel refreshed when they completed 6 cycles (9 hours). However one's individual cycle can vary by as much as 60 minutes, tips on how to tweak your habits will be discussed in the last chapter. For now, let's see how an average cycle looks like.
As shown, each cycle consists 5 major phases which can be mapped on a distinct brain pattern. Stages 1-4 will take 65 minutes, followed by a 20 minute REM stage in which one tends to dream. Some researchers suggest there is a short (5 min.) sixth phase where one is in a so-called twilight zone, where one is fully aware of external stimuli without conscientiously knowing. It is at this point one should awaken to feel fully refreshed, given that this person had sufficient completed cycles. Moreover, most of the time, hunger or a full bladder will trigger our brain to wake up at this point.
You can skip this part if not interested in the science behind sleep
As mentioned above, sleep comes with a reason on different levels. Both not-REM and REM phases of sleep are involved in memory consolidation. Very little new information is gained during sleep, but consolidation and maintenance of memory from experiences of the previous day is considerable. It is known that learning of visual information is improved during the first night of sleep and that sleep deprivation impairs recall of the information. Different types of sleep have a different effect on retention of information. The type of sleep also affects the type of information which is progressed by the brain. Dreams (found in REM-stage) are a manifestation of underlying brain activity and reflect the loose associative connections made during REM sleep. These loose associations are likely to result in increased creative mental activity and problem-solving abilities.
Furthermore, sleep may have some role in development of brain cells and connections between brain cells during development. It is the development of new neuronal networks during sleep that is responsible for new behaviours. Synchronisation of cortical activity during non-REM sleep may in some way coordinate cortical connections. During REM sleep the cerebral cortex is open to sensory inputs and forms loose associations that cannot be formed during wakefulness. Sleep has also been considered a restorative or a recovery phase that prepares the body for the next episode of wakefulness.
On the biochemical perspective, different hormones are secreted depending upon whether an individual is asleep or awake. Metabolic rate falls during non-REM sleep, energy is conserved and body temperature drops. During this period protein synthesis and the production of complex molecules within the body is increased. When we are awake our brain cells use a considerable amount of glucose to function and the intracellular glycogen stores become depleted. During sleep this process is reversed so that glucose is available during the next awekening.
To increase mental performance and cognitive abilities, one should learn which type of sleeping habit suits best. Most people have a natural tendency to be more alert in the morning or in the evening. The former are often referred to as early-birds, the latter are so called night-owls. Early birds often have their most creative moments short after their awakening, but are intolerant to nightshift work. Whereas night-owls are most productive the last hours before going to bed. To enhance alertness overday, a sleep monitor can be very useful. Monitor your sleep for two weeks and mark the days you felt well rested. In general 6 completed sleep cycles will provide you with many health benefits. Make note that when awakening in the midst of a REM stage makes you feel very tired. The motor output system is completely shut down during REM, so the brain needs some time to kickstart it. The monitor apps often come with a smart alarmclock which only will activate during light sleep.
Thanks for reading, make sure you follow my channel and up vote this article if you found it interesting!
Apps:
[https://itunes.apple.com/nl/app/sleep-cycle-alarm-clock/id320606217]
[https://play.google.com/store/apps/details?id=com.azumio.android.sleeptime]
References:
[http://neurosleep.org.au/]
[https://www.behance.net/gallery/30862107/The-Sleep-Cycle-Infographic]
[https://www.myvmc.com/anatomy/sleep-physiology/]
[https://www.nature.com/articles/nn1200_1225]
