Night Sleep and Long-Term Memory - Case Study Example

Long Term Memory Hypotheses: A good night sleep helps in restoration of long term memory. I am trying to find this out because there are conflicting views on this subject. Besides, the general tendency is to believe that sleep can help you feel better. However, I would like to find out whether sleep really has any effect on long-term-memory. Target Audience: Working executives who work over time and are deprived of sleep, executives who get to sleep peacefully, night shift workers and university toppers who study late nights as a way of life. Mode of Investigation: My Mode of research would be conduct a secondary research and find out the different views of researchers on this topic. After analyzing and validating their claims a pilot study will be conducted to test this hypothesis. This mode of investigation was chosen to blend theoretical as well as practical results on this subject. The pilot study will be conducted on people who have different sleeping habits. This will help me to determine what type of effect sleep has on restoring long term memory. Advantages of this method: Studying professional opinions on this subject will give me considerable know-how on this subject. The research and experiments done by scientists can be used as a reliable source to arrive at the above mentioned hypotheses. I will validate my secondary research based on the result of the pilot study. A pilot project will help in testing the hypothesis further. Disadvantages of this method: There is a possibility of misinterpreting the research works of scientists. Contradictory statements confusing models may lead my research on a wrong track. The target audience may not cooperate and may give false answers which may not be verifiable. The target audience may give answers which they believe to be true but may not necessarily be true. I did not choose other methods like performing scientific studies by myself because it would be difficult to get sanctions for proper laboratories and the apparatus required in performing such results. I also did not use the method of conducting surveys because, the audience that I am looking at would not have responded on their own. They were busy executives and thus I will have to personally go and meet them to get their views. Structure of this study: This study will first explain the underpinnings of Memory. It will explain the process of memory transfer and the role of sleep in restoring memory. It will state four experiments that will support the above hypotheses. This study will also be furnished with five view points of expert professionals on the importance of sleep for memory restoration. In the end, this essay will describe the pilot study that was performed to collect practical data. The questionnaire and the answers given by the participants will be analysed to arrive at a definite conclusion. There are three types of memories based on the amount of storage time. They are as follows: 1. Sensory Memory: This memory lasts only for milliseconds 2. Short Term Memory: This is also called working memory and lasts from a several seconds to a few minutes. Here information is not only stored but also processed (Baddeley and Hitch,1974) 3. Long Term Memory: Long term memory is memory that lasts anywhere between an hour to a lifetime. There are two types of memories. Procedural or Implicit and Declarative or Explicit (Squire, 1987). Procedural memory is defined as information we possess but cannot describe verbally. For example: skilled performances like driving heavy vehicles, playing guitar etc. Declarative memory refers to knowledge that can be expressed in speech or writing. Process It is believed that the incoming information is first held in sensory memory. This information is processed by the short term memory. The mnemonic and the rehearsal help in moving the short term memory into the long term memory through consolidation. (Restak, 2001). The working memory captures data for a short time until it is transferred to the long term memory. The temporary memory location for the declarative memory is assumed to be the hippocampus and the adjacent brain areas. A classic view of memory is that the hippocampus and the adjacent brain areas are necessary for encoding and storage of new memory traces. Eventually, these traces are consolidated and distributed elsewhere, especially the neocortex, so that the hippocampus is no longer essential for the retrieval of these long-term memories (Edwards, 2002) Role of sleep in capturing long term memory Since the storage capacity of short term memory is limited it is necessary that it transfers the data to the long-term memory. This task of transferring cannot be performed when the brain is awake. In waking period the working memory has to process large amounts of incoming information. Thus when the brain sleeps the working memory performs the task of transferring processes without interruption. The function of sleep is to process the received data, encode it and transfer to long-term memory. Experiments to understand the role of sleep: According to Jan Born (University of Lübeck,2007), a group of students were asked to learn triplets of words presented one after the other. Some were asked to sleep and some were not allowed to sleep. The students who slept were able to recall the order of the words better than those who were not allowed to sleep. Dr. Ellenbogen (American Academy of Neurology, 2007) conducted a study on 48 people (aged 18-3). They were asked to learn 20 pairs of words at 9 pm and were tested at 9 am the following morning after a nights sleep. The other group was given same words at 9am in the morning. They were tested on the same day at 9pm. The group that was allowed to sleep performed better than the group who didn’t have a chance to sleep. An experiment involving fruit flies has found that those in a social environment with at least 30 other flies slept four times as long during their daytime naps as flies in isolation. There was no difference in night-time sleep. The length of the nap increased with the size of the group they socialized with. Confirming that this effect was due to an increase in social interactions, rather than, for example, physical exhaustion from flying around more, flies deprived of their sight and sense of smell (meaning they could still fly around but could not socialize) showed no difference in daytime sleep patterns. Of 49 genes known to be involved in learning and memory, switching off seventeen (all related to long-term memory) made the flies sleep equally long regardless of whether they were social or not. This study was reported in the September 22 issue of Science. Society of Neuroscience performed an experiment to determine brain areas affected by lack of sleep. An experiment was conducted on 12 individuals to check if sleep deprivation affected their memory. Seven participants were made to sleep 4 hours a night for nine days. Five of them slept for eight hours. Each morning they were asked to complete a computer task which required memorizing a list of numbers. The list was one , three or five items long. Then participants were givena series of single digits and asdked to answer “yes” or “no” whether each digit were those they had memorized. The participants who slept for eight hours had increased their working memory efficiency whereas the ones who slept for 4 hours failed to show any development in memory efficiency. However, there was no effect on motor skills. Different views on the role of sleep in memory restoration: According to Ted Abel (Harvard University, 1993), one function of sleep may be to perform memory storage. By applying electrophysiological and behavioural approaches they have found that: Sleep appears critical for the storage of hippocampus dependent memories The molecular processes that regulate memory storage also regulate sleep According to Mark Greer (Monitor on Psychology, 2004), sleep boosts alertness. REM (Rapid Eye Movement) sleep is a way for the brain to store new information not long term memory. REM sleep is deep sleep and generally occurs at the end between the sixth and the eight hour of sleep. REM sleep replenishes neurotransmitters that organize molecular processes which are required for skill building like playing guitar or problem solving. According to the study conducted by Dennis Mcginty (Science Daily, 2008), deprivation of REM sleep in Rats affected their long-term memory. The experiment performed on Rats showed that cell proliferation was reduced by 63% of rats who were deprived of REM sleep. According to Dr. Jozseph Csicsvari and his colleagues sleep helps in reactivating latest waking experiences and converting them into long lasting memories. His team discovered that neuronal activities take place during sleep in the hippocampus. According to Stickgold, James, & Hobson, deep "slow wave" sleep is necessary to consolidate memories. Sleep is necessary to consolidate memories. Remembering a new task is more difficult if you don't sleep within 30 hours of learning the task. "Catch-up" sleep on subsequent nights doesn't make up for losing that first night's sleep. Moreover, it appears that the deep "slow wave" sleep that occurs in the first half of the night is the type of sleep necessary to consolidate memories. Other types of memory however, may require "REM" sleep (that occurs while you are dreaming). Pilot study To test this hypothesis I conducted a pilot study on a target audience. The profile of the target audience is given below: Working Executives: 10 working executives were interviewed and given a questionnaire to answer. These executives were typically high-ranking professionals who were extremely busy, travelled most of the time and worked on dead line projects. This group was chosen to test the hypotheses on people who were deprived of sleep. In spite of lack of sleep this group was performing well. The Questionnaire given to them included the following questions. 1. On an average how many hours did they sleep everyday? 2. Do they sleep peacefully or is it a troubled sleep? 3. Can they sleep while they are traveling at night? 4. How do they feel after travelling for a night without sleep? 5. Does lack of sleep affect their performance the next day? 6. Do they get REM sleep during the day or while travelling? 7. How good is their Memory? On a scale of 1 to 10, 1 being lowest and 10 being highest, how would they rate themselves? 8. What motivates them to stay awake? 9. Can successful performance compensate for lack of sleep? 10. Do they remember phone numbers and meeting dates in general? 11. Do they make use of reminders very often? 12. Do they rely on gadgets more than their memory? 13. Do they feel rested after a good night sleep if their work is pending? 14. Does pending work give sleepless nights? 15. Do they think lack of sleep affects their memory? Tally No 1: Answers to Questionnaire 1 Q.No1 5 6 5 5 7 6 5 5 6 5 Q.No2 yes yes no no yes yes yes yes yes yes Q.No3 yes no yes no yes yes no no yes no Q.No4 T NT T T NT NT NT NT NT T Q.No5 NA A NA A NA NA NA NA NA NA Q.No6 yes yes no yes yes no yes yes yes yes Q.No7 7 8 9 6 5 7 8 8 8 5 Q.No8 W F W F W W W W W F Q.No9 yes no yes yes no yes yes yes yes yes Q.No10 R NR NR NR R NR NR NR NR NR Q.No11 yes no no no yes no no no no no Q.No12 yes yes yes yes no yes yes yes yes yes Q.No13 Yes no yes no yes yes no no no no Q.No14 Yes no yes no yes yes yes yes yes yes Q.No15 no yes no no yes yes no yes no yes T: Tired NT: Not Tired NA: Not Affected A: Affected R: Remember NR: Not Remember The explanation and analysis of the questions is given below: Question No1 was asked to get an estimate of how many hours the executives generally slept. The number of hours would give an idea as to how many minimum hours are required to survive. The interviews confirmed that on an average, most of the busy executives slept for six hours. Question No 2 was asked to determine whether most executives slept peacefully or not. There is a general assumption that busy executives with lot of work tend to get disturbed sleep. Contrary to this belief, the pilot research showed that these executives slept peacefully most of the time. Although they managed to get six hours on an average they slept peacefully. Question No 3 was asked to know whether these executives were in a position to sleep while they were travelling. The answer would give an insight into the assumption that executives cannot sleep while they travel. The Answers showed that most of the executives managed to get small naps while on airports or while travelling in taxis. They are so tired that the moment they close their eyes they fall asleep. Six hours of sleep is not possible on such days. Some times they go without sleep for 24 hours. These executives however manage to get REM sleep in whatever hours they get. Question No 4 was asked to get a feedback on the feelings on the next day of travel. The answer to this question varied a lot. Some felt tired and groggy whereas others were upbeat and ready to perform. This data helped to determine that feeling of grogginess or excitement is not dependent on gain or lack of sleep. It is dependent on the type of work for which you have remained awake. If the work is interesting, there is no tiredness. If the work is tiring there is a feeling of drain. Question No 5 was asked to determine the effect of sleep on performance. Again the answer to this question varied. Some people felt that sleep had nothing to do with performance and some felt very tired and unwilling to perform. People who were forcibly kept awake to deliver an assignment would not perform satisfactorily whereas people who stayed awake on their own initiative performed better. Thus it was revealed that sleep doesn’t determine performance. It is the attitude and willingness towards work that affects performance. Question No 6 was asked to analyze whether REM can be obtained during day hours or only at night? The answer to this question revealed that REM sleep can be achieved at any time of the day. A power nap in the afternoon can refresh an individual as good as a night’s sleep. Thus it is not necessary to get the sleep at night. A day time nap could also perform the same functions. Question No 7: This question was asked to determine whether this audience rated themselves badly on their memory. Surprisingly most executives rated their memory above 5. Most of them believed that they had good memories inspite of lack of sleep. Question No 8. This question was asked out of curiosity. The answer varied a lot. Some stayed awake because they had no choice. Some loved their work so much that staying awake did not matter to them a lot. Some were indifferent towards whether they got sleep or not. Question No 9. This Question was asked to check if success could compensate for lack of sleep. The answer varied again. Some were perpetually disturbed for not being able to get sleep whereas; others were not bothered once they achieved desired results. Question No 10 was asked to validate their claims of having good memory. This specific question gave answer to a very important point. Most of them did not remember phone numbers. Although it should be noted that nobody made an effort to remember them. They dialled directly from their cell phones. However, they did not clearly remember their appointments. They had to maintain a diary to remember appointments. This showed that their memory was not so sharp. Question No 11. This question was again asked to determine whether they rely on their memory or take aids to remember important tasks. The answer showed that most of them relied on external gadgets to remind them. They depended less on their memories. Phone numbers were stored on cell phones. Appointment calendars were maintained to remind them of their future appointments. Pop-up windows were designed to come up on the computer screen to attend to important tasks. Different types of beeps were installed for reminding different categories of work to be completed. Question No 12. This question was given to them just to make them realise that they depended more on gadgets than on memory. It was a fun question with no particular help from the answer. Question No 13 was asked to determine whether lack or gain of sleep really had any effect on their next day. The answer varied again. The determinant was not sleep but the type of work they did. Question No 14 .This question was asked to check whether executives could sleep inspite of pending work. Most of them slept irrespective of their work being complete or not. Most of them slept irrespective of pending work. Only some of them were not able to sleep if they had work pending. Sleeping at night is more of a habit with people. Their biological clocks are set. At a definite time people do feel sleepy and sleep irrespective of the pending jobs. Some participants believed that by sleeping properly they were able to complete their pending work within less time. Question 15 was asked to take a general consensus on what they think was the role of sleep in restoring memory. Most of them said sleep was necessary to feel refreshed. They were however not willing to agree that sleep had anything to do with their memories. These were high ranking professionals at high positions considered very successful by the society. There was no possibility of their committing to having a bad memory. Most of them believed that they were successful because of their mental abilities. I prepared another questionnaire to interview the night shift workers. The questionnaire was as follows? 1. How many average hours do they sleep per day? 2. Do they sleep continuously or with breaks in between for food? 3. Do they feel refreshed and upbeat all the time or do they feel groggy? 4. How do they rate their memory on a scale of 1 to 10, 1 being lowest and 10 being highest 5. Do they think sleep had anything to do with having better memory? Tally2: Answer sheet of Questionnaire 2 Question No 1 7 8 6 7 8 Question No 2 With Breaks Continuous With Breaks With Breaks With Breaks Question No 3 Refreshed Refreshed Groggy Groggy Refreshed Question No 4 7 6 7 5 8 Question No 5 No No No No Yes The explanation of the answers and their analysis is given below: These groups of people were not easily available to answer surveys. Most of them were sleeping after a night shift. Only 5 such people were contacted. The numbers of questions in the questionnaire were reduced to five because this group of people was not keen on filling the forms and sending them back. They preferred to answer the questions on the spot and finish off the episode. Thus other questions were more or less the same questions which the busy executives had answered. The answer to the first question was surprising. This group of people slept for more than 8 hours. Question no 2 was asked to find out whether they could sleep at a stretch during day hours. The answers to this question revealed that most of them could not sleep continuously at one stretch. They got up in between, had their meals and went back to sleep. Unlike people who slept at a stretch at night, these participants did not get continuous undisturbed sleep. Since they were sleeping during day time, they got up to have their meals, go to the bathroom, attend to doorbells etc. It seemed almost impossible to sleep for longer stretches during day time. Question No 3 was asked to check whether lack of sleep affected their feelings. The answers were more or less like the busy executives. Sleep was not a major factor that determined their mood. Performance and willingness to perform was more important. They did feel groggy immediately after waking up, but soon adjusted to events without trouble. Question No 4 This question was asked to find how they rated themselves. Most of them rated themselves high. It seems nobody wants to commit to having a bad memory. Answer to this question could not be taken as reliable. People who worked late night shifts were aware that they worked in opposition to their biological clocks. They also seemed to be aware of the health hazards involved in reversing the natural sleeping pattern. However, they appeared defiant and ready to argue that sleeping during day time made any difference to their memory. Since it was their job to be awake at night, they had accepted this fact and had conditioned their minds to believe that they were functioning normally. They were not willing to admit that such habit could have any effect on their memory. Some participants even showed their good performance appraisals and growth chart to assure that sleep patterns did not affect their mental abilities. Question No 5 was asked to get a general consensus on this topic. The answers were divided. Two of them felt sleep was important in restoring memory whereas three of them denied the role of sleep in memory. I interviewed the third group in the university. These were university students who generally did well in their exams and preferred to stay awake late nights to study. This group was not given any questionnaire. This was an informal chat to understand their behaviour patterns and their requirement of sleep. The results obtained from these chats were varied in nature. Most scholars who studied at night managed to catch up on their sleep some time during the day or on other nights. Some scholars preferred to sleep well and wake up early to study. They said studying in early morning hours helped them remember better than studying late night. Some required 6 hours of sleep whereas others required 8-10 hours of sleep. There was no symmetrical pattern to arrive at a definite conclusion. All these scholars had very good memories and they topped the exams most of the time. After listening to their opinions it appeared that sleep may not really be important in restoring long term memory. However, there was no scientific way to find out whether this was true. It was not possible to conduct scientific experiments on this group due to lack of availability of same students. The research stated by scientists and professionals, however maintain that sleep do have profound impact on restoration of memory. Conclusion of Pilot study: The pilot study revealed contradictory answers. It was however possible to determine that sleep was essential for well-being. Whether it helped in restoration of memory or not could not be concluded based on the pilot study. The research from secondary sources contains professional view points. They do agree that sleep is essential in restoration of memory. The final result of this hypothesis could be stated that sleep is necessary for restoration of memory. However it is not important whether it is good night sleep or good day sleep. Any sleep can help in letting the working memory do its functions and restore long term memory. References Baddeley, A.D. and Hitch G, In the Psychology of learning & Motivation, Academic Press, 1974, 48-79 Dr. Jeffrey Ellenberg, American Academy of Neurology, may 2004 http://www.eurekalert.org/pub_releases/2007-04/aaon-ssy040307.php Dr. Ted Abel, Department of Biology, Harvard University, October 2006 http://www.bio.upenn.edu/faculty/abel/ Dr. Ellenbogen, Sleep strengthens your memory, American Academy of Neurology, April 2007, http://www.eurekalert.org/pub_releases/2007-04/aaon-ssy040307.php Four Days of REM Sleep Deprivation Affects Forebrain, Long-term Memory in Rats, Science Daily, 6 February 2008, http://www.sciencedaily.com/releases/2008/02/080201085713.htm Good Nights sleep boost long term memory, http://www.shyiam.com/archives/51 Jan Born, Sleep enforces the temporal sequence in memory, April 2007 http://www.eurekalert.org/pub_releases/2007-04/plos-set041707.php Long term Memory, Wikipedia http://en.wikipedia.org/wiki/Long-term_memory Long term memory http://www.cognitivemap.net/HCMpdf/Ch13.pdf Mark Greer, Strengthen your brain by resting it, Monitor on Psychology, August 2004 http://www.apa.org/monitor/julaug04/strengthen.html Medical Research Council, A good night’s sleep could improve long- term memory, January 2008. http://www.mrc.ac.uk/consumption/groups/public/documents/content/mrc004321.pdf Raymond Edward , where is memory, Medscape Portals Inc, 2002 Restak R, The secret life of the brain, The Dana press & Joseph Henry Press, 2001 Squire, L.R, Memory &brain, New York, Oxford University Press, 1987 Scientists find brain areas affected by lack of sleep, Society for Neuroscience http://www.eurekalert.org/pub_releases/2003-11/sfn-sfb_1111003.php Stickgold, R., James, L. & Hobson, J.A. 2000. Visual discrimination learning requires sleep after training. Nature Neuroscience Read More

Process It is believed that the incoming information is first held in sensory memory. This information is processed by the short term memory. The mnemonic and the rehearsal help in moving the short term memory into the long term memory through consolidation. (Restak, 2001). The working memory captures data for a short time until it is transferred to the long term memory. The temporary memory location for the declarative memory is assumed to be the hippocampus and the adjacent brain areas. A classic view of memory is that the hippocampus and the adjacent brain areas are necessary for encoding and storage of new memory traces.

Eventually, these traces are consolidated and distributed elsewhere, especially the neocortex, so that the hippocampus is no longer essential for the retrieval of these long-term memories (Edwards, 2002) Role of sleep in capturing long term memory Since the storage capacity of short term memory is limited it is necessary that it transfers the data to the long-term memory. This task of transferring cannot be performed when the brain is awake. In waking period the working memory has to process large amounts of incoming information.

Thus when the brain sleeps the working memory performs the task of transferring processes without interruption. The function of sleep is to process the received data, encode it and transfer to long-term memory. Experiments to understand the role of sleep: According to Jan Born (University of Lübeck,2007), a group of students were asked to learn triplets of words presented one after the other. Some were asked to sleep and some were not allowed to sleep. The students who slept were able to recall the order of the words better than those who were not allowed to sleep. Dr. Ellenbogen (American Academy of Neurology, 2007) conducted a study on 48 people (aged 18-3).

They were asked to learn 20 pairs of words at 9 pm and were tested at 9 am the following morning after a nights sleep. The other group was given same words at 9am in the morning. They were tested on the same day at 9pm. The group that was allowed to sleep performed better than the group who didn’t have a chance to sleep. An experiment involving fruit flies has found that those in a social environment with at least 30 other flies slept four times as long during their daytime naps as flies in isolation.

There was no difference in night-time sleep. The length of the nap increased with the size of the group they socialized with. Confirming that this effect was due to an increase in social interactions, rather than, for example, physical exhaustion from flying around more, flies deprived of their sight and sense of smell (meaning they could still fly around but could not socialize) showed no difference in daytime sleep patterns. Of 49 genes known to be involved in learning and memory, switching off seventeen (all related to long-term memory) made the flies sleep equally long regardless of whether they were social or not.

This study was reported in the September 22 issue of Science. Society of Neuroscience performed an experiment to determine brain areas affected by lack of sleep. An experiment was conducted on 12 individuals to check if sleep deprivation affected their memory. Seven participants were made to sleep 4 hours a night for nine days. Five of them slept for eight hours. Each morning they were asked to complete a computer task which required memorizing a list of numbers. The list was one , three or five items long.

Then participants were givena series of single digits and asdked to answer “yes” or “no” whether each digit were those they had memorized. The participants who slept for eight hours had increased their working memory efficiency whereas the ones who slept for 4 hours failed to show any development in memory efficiency. However, there was no effect on motor skills. Different views on the role of sleep in memory restoration: According to Ted Abel (Harvard University, 1993), one function of sleep may be to perform memory storage.

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