A science teacher explains: How is sleep related to memory?

Albert Einstein slept for 10 hours besides taking siestas during the day. Even icons like Elon Musk and Jeff Bezos ensure six to seven hours of sleep.

By Rachna Arora

In the world we live in today, lack of sleep is considered a hallmark of hard work and an essential ingredient for achieving success. We often come across students and professionals taking pride in scarce hours of sleep, sporting it as a badge of honor and implying this a march towards inordinate accomplishments. As a society we have developed an extremely high tolerance for sleep deprivation blissfully ignoring this being a critical component of our well-being.

Sleep embodies our mental and physical recovery period leading to a productive, energetic and happy work day. The case in point is an eye-opening research conducted in the Massachusetts Institute of Technology, US in 2019. The students who consistently had a good night’s sleep and refrained from pulling an all-night out before exams scored far better than those who had erratic sleep habits.

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Memory formation and learning is primarily a three-step process, with information acquisition, consolidation, recall and application as needed. While gaining, use and retrieval of information happens when we are awake, amalgamation of knowledge, strengthening and integrating the new understanding with the preexisting data primarily happens when we are asleep.

When we obtain information, foremost the sensory memory is formed with the help of five sense organs. This learning is processed by the nervous system and stowed to short term memory. Just as a smartphone or a laptop comes with a limited storage capacity (RAM), so does our short term memory. So, important and relevant reminiscences need to be continuously transferred to the long-term memory site. For example, we remember the number of the cab while waiting for its arrival but forget it soon after as the information remains in the short-term memory but we do not forget our mobile number as this vital information has been moved to the long-term memory, which perhaps has infinite storage capacity.

Although still an area of continued research, there is some consensus between sleep and memory. Scientists and researchers say that every stage of sleep plays a role in memory formation.

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While sleep is a restful time for the body, the brain remains busy as we pass through sleep cycles comprising REM or Rapid eye movement sleep and Non-REM sleep. As we fall asleep, we first enter the Non-REM cycle which comprises three stages. While in stage one we drift into sleep, stage  two is characterised by deep sleep and stage three is characterized by very deep sleep. Have you ever been woken up suddenly and felt bleary and confused for a while? Then you must have been woken from stage three sleep. Then comes the important REM sleep. Each sleep cycle takes about 90-120 minutes, and REM sleep is for about 10 minutes, this duration goes up to one hour during the subsequent sleep cycles.

As we sleep, the slow brain waves in stage two and three of non-REM sleep transfer the memories from the hippocampus, which is the temporary storage site to permanent storage locations. The slow brain waves also help to consolidate declarative or fact-based memory, which may be autobiographical and also help remember what is termed as common knowledge. During the REM sleep, neuron connections which help in critical and creative thinking are strengthened. REM sleep is also important for consolidation of procedural memory which helps us perform tasks on autopilot. Lighter stages of sleep help to cement motor learning which involves muscular coordination like brushing our teeth.

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Although there is no doubt that sleep is indispensable for memory and learning, its exact role is open to debates and many competing theories have been proposed to explain the relation. However, what we know for sure is that adequate sleep replenishes our ability to learn, improves memory, retention and recall of information, problem solving skills and bolsters our creativity. Lack of sleep makes one cranky, acting as a potential invitation to lifestyle ailments like diabetes, heart problems, anxiety and depression with severe adverse consequences for memory and learning.

Albert Einstein slept for 10 hours besides taking siestas during the day. Even icons like Elon Musk and Jeff Bezos ensure six to seven hours of sleep. So when we have a good night’s sleep, we are getting ready to realise our potential. It is imperative to promote healthy sleep habits. Just as we propagate the ill-effects of smoking and junk food, it is essential to treat sleep as a physical and mental health issue and promote a vigorous sleep culture. The task is difficult in the era of gadget addiction but essential if we do not want to add unproductive, perennially tired and exhaustive people to the workforce.

No wonder sleep besides diet and exercise forms a potential triumvirate for a healthy mind and body.

(The writer is PGT- Physics at Shiv Nadar School, Noida.)

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