Increment In Cognitive Function By Sleep Quantity

Background

Discuss about the Increment In Cognitive Function By Sleep Quantity.

Crisis at the performance of daily activities from sleep deprivation is a universal occurrence. In the current study, it was hypothesized that the magnitude of sleep over a period of 24 hours and 7 days was positively correlated with the cognitive performance of human memory in a statistically significant manner.

A physiologic and cognitive ability of the cohort of 156 participants was evaluated in the current study. The recent exploration was based on the digit span test, which the participants of the University of Murdoch performed for the purpose of the experiment. The evaluation process of the digit span test was based on the average memory span of the participants, who were aged around 25.65 8.4 years.

The sleep quantity of the respondents was taken into measurement in two scenarios. First, the respondents' sleep hours for the last 24 hours were measured, and then, total sleep hours of last seven days were considered. The cognitive ability from the test was found to be positively associated with average sleep hours for the last seven days, whereas no association was found between the sleep hours of last night and cognitive performance.

Conclusion

The current work quantified the affirmative impact of rest and sleep on the physiologic and cognitive performance, but the immediate sleep impact on the cognitive ability did not get established here.

Sleep quality and duration have always demonstrated a non-monotonic relation with satisfaction level and success intensity in the work field. Rene Descartes, once in his "Meditations", exclaimed about the certainty of being awake. Researcher believed the reason for sleep as fatigue until the mid 20^th century. The exact biological reason for turning off from productive awakening is still a theory of disagreement for the scientist. The benefits of sleep are apparent, though depleting impacts are still researched for establishing the necessity of rest and sleep requirement for a human brain. Problems related to fewer hours of sleep or rest have been the subject matter of focus from many decades. The adverse effect on cognitive performance of young human brains due to lack of sleep hours has been intensively explained form various angles by numerous researchers.

Chee et al. in 2008 summarized the adverse effect of sleep deprivation on the performance of working memory by functional imaging method. Human brains, which got substantial sleep and rest performed better in functional imaging. Jessica Payne explored the consequences of sleep quantity on selective memory which was related to emotional scenes. The time delay of sleeping time of the experimental subjects after the encoding of discerning consolidation of information was established as a statistically significant factor. The complex interpretation of the selective information consolidation was found to be positively associated with the sleep hours of the subjects. The current study was also oriented around the correlation of the sleep hours and cognitive performance of the subjects, but post sleep impact was evaluated here. The impairment of the working memory due to sleep deprivation and diminution of the hippocampal AMPA receptor was analyzed by Roelina Hagewoud et al. in 2010. Hippocampus related capacity to learn and generation of fresh memories were found to be adversely impacted by lack of sleep hours. Even, twelve hours of sleep deficiency was scrutinized as an unfavorable factor for cognitive function.

Method

The complexity in performing the learning and comprehensive responsibilities is deciphered by the coalesce system of the human brain, which is referred to as the working memory of the human mind. The accumulation of temporary or short-term information is believed to be the fundamental conception of working memory (Baddeley, 2010). Lim et al. in 2010 conducted a research to comprehend the impact of lack of sleep on cognitive functions of the working memory. Six diverse cognitive fields of tests were utilized to measure the counter effect of short-term lack of sleep of the participants, and wake time was found to be the statistically significant predicting factor for the effect of sleep deprivation (SD) on cognitive performances. The extensive implications of insufficiency of sleep were also analyzed by William Killgore in his thesis on sleep deprivation, in 2010. He discussed the less talked impacts of SD on the critical cognitive abilities of the brain. Impact on the execution of complex works; perception supremacy and recollection ability were primarily discussed. The debate based on the global and selective effect of SD and ability like decision making was found to be unaffected by lack of proper sleep.

Based on these previous hypotheses, the primary aim of the scholar in the current work was to establish the relation of working memory with average sleep quality or hours of the subjects. The space produced by the previous conjectures was the rationale of the current investigation. This psychoanalysis by the scholar investigated two hypotheses related to the assumed positive effect of sleep quality on memory performance. Firstly, it was hypothesized that sleep hour of the previous night is positively related to cognitive performance. Secondly, the association between the average sleeping hours of the last seven days was hypothesized to be a statistically significant factor in the performance of the working memory. The participants were informed about the intricacies of the digit span test, and their cognitive ability was assessed through the mean number of recalls in the experiment

Every one of the participants was from the University of Murdoch, aged between 18 years to 56 years. Among the 156 participants, 47 were males and the rest of the 109 members was female. The average age of male participants was 23.55 years (SD = 4.32 years) and the average age of female participants was 26.55 years (SD =9.53 years). The 95% confidence interval of the male age (22.29, 24.82) and female age (24.74, 28.36) revealed that most of the participants belonged to the youth age group.

Result

University notice boards were utilized for this purpose, an advertisement for the program with a short description was published. The research team also distributed handouts to the students and instructors of the university. For the cognitive component of the experiment, the digit span test was used. Two sets of forward digit counting, and again two set of backward digit counting with ten trails in each of the sets were used as an instrument for testing the cognitive performance of the participants. The longest numerical series successfully recalled by the subjects was taken as the measure of cognitive performance. The average score from these four sets of digit counting was taken as the memory span.

All the students and instructors of the University of Murdoch were informed about the research program. The participants were recruited by the scholar and the research team through a small interaction session. Willing participants with a history of mental illness were excluded from the scope of the experiment. The engaged participants were explained about the scope of the research. The digit span test was elaborated in details and the scoring methodology was also explained. The research team distributed forms to the participants, where detailed information including demographics and sleep quantity for the last 24 hours and last 7 days were to be filled. The completed forms were collected and cross-checked for final selection list. For final participation, the participants were required to sign a consent form approved by the Institutional Ethical Committee.

The sleep quality in total and average hours for 156 participants was found from the filled up forms. Average sleep hours for the last 24 hours was calculated as 7.19 hours (SD = 1.68 hours), which ranged from 3.0 hours to 12.0 hours. The average sleep hours for the period of the last seven days was calculated as 7.38 hours (SD = 0.93 hours), which ranged from 4.86 hours to 10.29 hours. The mean score for the digit span test of the participants was computed as 6.43 (SD = 1.18) with a range of 3.75 to 9.5 words. A correlative study was performed between the memory span scores and sleep quality of the subjects. There was a statistically significant (p < 0.05) low positive correlation (r = 0.16) between average memory span and sleep quality for past seven days. Although, there was no statistically significant (p = 0.07) correlation (r = 0.14) between average memory span and sleep quality of last 24 hours or the previous night. The pattern of sleep amount was though confirmed from the statistically significant (p < 0.05) high positive correlation (r = 0.59) between the 24 hours and past seven days' average sleep hours.

Conclusion

The low positive, but significant correlation between the sleep quality of the past seven days and average memory span explained the previous research hypotheses. The null hypothesis of the current study was established here. Although, the null hypothesis about the association of sleep quality of past night and average memory span got rejected. The basis was the pieces of evidence from the correlation coefficient.

Cognition refers to a range of mental processes which includes memory, language, problem-solving, attention and forward planning. Cognitive capabilities have been seen to be affected by the inadequacy of sleep. The scope of current work can be quantified by the affirmative impact of rest and sleep on the physiologic and cognitive performance. In a previous research which studied cognitive capabilities with sleep duration, included caffeine being an effective manipulator of mental state (Snel & Monicque, 2011). Caffeine was found to be able to enhance the levels of wakefulness in a deficiency of sleep. The affirmative effect was visible on performance in the cognitive task, which downsized the degraded response time due to sleep deprivation. It is a well-known antagonist of adenosine receptor which allows modulating mental state. Lo et al. in 2012 revealed the effect of SD and circadian misalignment on cognitive executions. The modulation due to circadian phase was absent in the current study, which could have enacted in a positive way in correlating the experimental pieces of evidence. 

The study was conducted with a limited population, where varied age groups were not taken into consideration. It is a well-known fact that especially the sleep duration subsequently decreases with aging. However, the immediate sleep impact on the cognitive ability did not get significantly clarified here. A study of a wide population with more factors connected with cognitive capabilities could establish the results of the study in a better manner, which was beyond the scope of the current research (Best & Kahn, 2016).

The current scope of research does not take into consideration intricate details such as the timing of sleep, the class timing of the students and health issues as factors. Delayed class timing was found to be one of the important reasons for better brain development in children (Minges & Redeker, 2016). Areas of future research were understood once varied literatures related to these areas were evaluated. Another possible area of future research includes analyzing varied cognitive functions such as memory, reasoning, and vocabulary. Impacts of various cognitive related diseases such as dementia, Alzheimer’s on sleep duration which in turn affects cognitive capabilities of an individual also requires in-depth analysis (Rizzo et al., 2010). Van der Donk et al. in 2015 worked with children with ADHD and attention in class. Improvised interventional seeking was the primary of that work. The detrimental effect of the emotional impact of the human brain, especially for young minds was also not taking account of in the current work, which could provide a general conclusion for the cognitive performance (Scheibe & Blanchard-Fields, 2009).

Methodology: Participants

 The implications of this research can be multifarious as it can have application in management, medical and other domains. Expanding the scope of this current study can help reveal sleep disorders which in turn affects cognitive capabilities, for understanding mental capabilities. Cognitive neuroscience and sleep neurobiology have recognized the importance and role of sleep in cognition. Studies conducted by various well-known scholars reveals that sleep disturbances, decrease in the amount of continuous sleep, the amount spent on quality sleep affects cognitive impairments. There have been pieces of evidence of associations of sleep disturbances with the earliest signs of neurodegenerative disorders such as Alzheimer's diseases (Albert et al., 2011). Various cross-sectional studies conducted on short and long-sleep duration has been found to be associated with cognitive and memory functioning. Disturbed sleep had been also found associated with diminished cognitive functioning. Long-term sleep disturbances were found to be associated with varied risk factors primarily associated with cognitive capabilities which might arise from mid to late adulthood period (Johnson et al., 2017).    

Conclusion

The current approach adopted by the study provides long-term sleep deprivation as a significant and vulnerable factor for poor cognitive functioning. However, no such implication was found with sleep hours of immediate previous at night. Further research was required in order to incorporate the findings with the general population with other uncontrolled factors.

References

Albert, M. S., DeKosky, S. T., Dickson, D., Dubois, B., Feldman, H. H., Fox, N. C., ... & Snyder, P. J. (2011). The diagnosis of mild cognitive impairment due to Alzheimer’s disease: Recommendations from the National Institute on Aging-Alzheimer’s Association workgroups on diagnostic guidelines for Alzheimer's disease. Alzheimer's & dementia, 7(3), 270-279.

Baddeley, A. (2010). Working memory. Current biology, 20(4), R136-R140.

Best, J. W., & Kahn, J. V. (2016). Research in education. Pearson Education India.

Chee, M. W., & Chuah, L. Y. (2008). Functional neuroimaging insights into how sleep and sleep deprivation affect memory and cognition. Current opinion in neurology, 21(4), 417-423.

Hagewoud, R., Havekes, R., Novati, A., Keijser, J. N., Van Der Zee, E. A., & Meerlo, P. (2010). Sleep deprivation impairs spatial working memory and reduces hippocampal AMPA receptor phosphorylation. Journal of sleep research, 19(2), 280-288.

Johnson, D. A., Lane, J., Wang, R., Reid, M., Djonlagic, I., Fitzpatrick, A. L., ... & Redline, S. (2017). Greater cognitive deficits with sleep-disordered breathing among individuals with genetic susceptibility to Alzheimer disease. The multi-ethnic study of atherosclerosis. Annals of the American Thoracic Society, 14(11), 1697-1705.

Killgore, W. D. (2010). Effects of sleep deprivation on cognition. In Progress in brain research (Vol. 185, pp. 105-129). Elsevier.

Lim, J., & Dinges, D. F. (2010). A meta-analysis of the impact of short-term sleep deprivation on cognitive variables. Psychological bulletin, 136(3), 375.

Lo, J. C., Groeger, J. A., Santhi, N., Arbon, E. L., Lazar, A. S., Hasan, S., ... & Dijk, D. J. (2012). Effects of partial and acute total sleep deprivation on performance across cognitive domains, individuals and circadian phase. PloS one, 7(9), e45987.

Minges, K. E., & Redeker, N. S. (2016). Delayed school start times and adolescent sleep: a systematic review of the experimental evidence. Sleep medicine reviews, 28, 86-95.

Rizzo, M. R., Marfella, R., Barbieri, M., Boccardi, V., Vestini, F., Lettieri, B., ... & Paolisso, G. (2010). Relationships between daily acute glucose fluctuations and cognitive performance among aged type 2 diabetics. Diabetes care.

Scheibe, S., & Blanchard-Fields, F. (2009). Effects of regulating emotions on cognitive performance: what is costly for young adults is not so costly for older adults. Psychology and aging, 24(1), 217.

Snel, J & Lorist, Monicque. (2011). Effects of caffeine on sleep and cognition. Progress in brain research. 190. 105-17. 10.1016/B978-0-444-53817-8.00006-2.

van der Donk, M., Hiemstra-Beernink, A. C., Tjeenk-Kalff, A., Van Der Leij, A., & Lindauer, R. (2015). Cognitive training for children with ADHD: a randomized controlled trial of cogmed working memory training and ‘paying attention in class’. Frontiers in psychology, 6, 1081.