Sleep: Essential for Memory and Creativity

Introduction

Sleep occupies one-third of human life and is one of the most important human behaviors (Wei, 2016). Oxford Dictionary (2010) defines sleep as a periodic condition of relaxation for the mind as well as the body during which the eyes usually close, metabolic rate is reduced, and consciousness is completely or partially suspended to diminish responsiveness to things happenings in the environment. Rigorous studies by Cai et al. (2009) have established that sleep highly advances learning and creativity. It has therefore been hypothesized that sleep triggers memory-processing activities that aid in consolidating and strengthening memory integrals thereby improving creative capacities (Walker and Stickgold, 2017). Consequently, extensive conflicting theories have been proposed to explain the universal role of sleep. According to Assefa et al. (2015), the leading theories on sleep function include memory consolidation theory, conservation of energy theory, restorative theory, and early brain development.

Theories on Sleep Functions

Memory Consolidation Theory

Jenkins and Dallenbach (1924) were the first to provide empirical evidence that sleep improves memory consolidation. Participants were asked to learn nonsense syllables over certain periods. They found that the number of syllables reproduced was twice as good after intervals of sleeping compared to after interval of waking (Jenkins & Dallenbach, 1924). Underlining the conclusion that sleep improves memory consolidation are numerous studies (Ashworth et al 2014; Wei et al., 2016;Rasch & Born, 2013) have shown that while we sleep, memory is consolidated through complex integrated memory tasks. Ashworth et al. (2014) conducted a study in children to explore the effects of sleep-related properties on dual tasks that were a non-word education task as well as the "Tower of Hanoi" intellectual conundrum. In their study, Ashworth et al. (2014) observed 33 children aged between 6-12, where actigraphy was employed to examine their sleep. Memory consolidation based on sleep was examined by use of non-word tasks and the cognitive puzzle of the Tower of Hanoi (Ashworth et al., 2014). The children were exposed to two tasks and subsequently tested after intervals of sleep and wake. The students displayed significant enhancements of around 14.5% on the non-word knowledge chores as well as 25% of the "Tower of Hanoi" chores after sleeping (Ashworth et al., 2014). Nonetheless, there was no substantial difference in results after the wake retention interval. Therefore, the authors concluded that adequate sleep was obligatory for the consolidation of explicit memory (Asworth et al., 2014).

Conservation of Energy

Studies by Jung et al., (2010) and Schmidt (2017) further correlated sleep with conservation of energy. Energy conservation theory holds that period of inactivity in the form of sleep amongst mammals and birds leads to a reduction of energy demand and expenditure (Schmidt, 2017). In the case of human being, metabolism is reduced by 10 % during sleep (Schmidt, 2017). Effective and efficient use of energy resources is crucial for the survival of animals. Evidently, the ability of species to utilize effectively their energy resources by lowering metabolic resources provides them with survival advantages over other members of the same species. Consequently, Jung et al., (2010) asserted that sleep is essential for limitation of energy expenditure that is lower when animals are at rest.

Early Brain Development

Additionally, rigorous research by Dahl (2007) has further identified sleep as an essential component in the developmental stages of the brain. It, therefore, follows that babies need more sleep than adults do since their brains are still at the developmental stages. In addition, according to Dahl (2007), the pituitary glands discharge hormones that are indispensable for tissue development during phase four of sleep. The Millennium Cohort Study, which followed more than 10,000 children over the course of a decade showed that children with irregular bedtimes up to the age of three had poorer results when their reading, math skills, and spatial awareness were tested (Centre for Longitudinal Studies, 2017).

Effects of Sleep Deprivation

Sleep deprivation highly interferes with the optimal performance of the body. Sleep deprivation has strongly been related to impairment of body processes and human errors (Bianchi, 2014). Studies have indicated that short-term to chronic sleep deprivation has detrimental effects on the body both physically and mentally (Orzeł-Gryglewska, 2010). Harmful effects of sleep deprivation generally include physical damage, mental damage and causing harm to other in form of accidents. Physiological effects of sleep deprivation include heart attack and increased high blood pressure, obesity and hallucinations (Orzeł-Gryglewska, 2010). Studies by Mello et al. (2013) further found an association between sleep and immune system. Sleep deprivation weakens the immune system of the body thereby individual become vulnerable to disease and infections (Bianchi, 2014). Additionally, Mello et al. (2013) noted that insufficient sleep was amongst the major contributors of traffic accidents globally. Furthermore, research by Wolfson and Carskadon (1998) showed that school grades were likely to decrease due to sleep deprivation related problems that majorly affected the teenagers.

Wolfson and Carskadon (1998) conducted a study with the objective of explaining the correlation between teenagers' sleeping, waking habits and their characteristics that include sex, age, and school as well as daylight operations. Analysis of the characteristics incorporated mood, behavior and school performance (Wolfson and Carskadon, 1998). They concluded that students with better grades were the ones that had more overall sleep as well as earlier bedtimes while in school nights than learners who had inferior grades. Nevertheless, a study of children that aimed to find a correlation between sleep duration and obesity showed that there was a strong correlation between the amount of sleep and weight for the children aged 4-7 years old (Lytle, Pasch and Farbakhsh, 2010). It emerged that the less nigh time sleep the children had, the higher the risks of being overweight whereas for daytime sleeping there was no correlation (Lytle et al., 2010). In addition to preventing overweight, sleep has also been linked to improved creativity particularly at the developmental stages of children (Ritter et al., 2012).

Sleep and Creativity

The correlation between sleep and creativity has been studied for decades. Anecdotal evidence shows that artists, musicians, inventors, and writers such as Beethoven and Paul McCartney have used the hypnagogic state, which is the stage between wake and sleep, to gain inspiration (Wagner, Gais, Haider, Verleger & Born, 2004). In 2004, Wagner et al., conducted a study to examine how sleep affects a person's ability to gain insight using a number reduction task. The results showed that those who slept during the night had more insight than the ones staying awake during the night or the day (Wagner et al., 2004). According to Ashworth et al, (2014) and Brand et al (2011) undertaking sleep after encountering a problem allows our brain to process the problem and eventually come up with a solution. It has also been shown that rapid eye movement (REM) sleep increases the creative process by helping the formation of new associative systems in the brain and beneficial links between thoughts, operating as a facilitator for creativity (Cai et al., 2009). Moreover, Horne (1988) conducted a study to assess the negative effects of sleep loss, 12 participants went 32 hours without sleeping whereas 12 participants slept normally. The results of Horne (1988) study showed that sleep deprivation compromised performance on all test scales. Overall, sleep-deprived individuals were prone to be less creative. A study conducted by Dewald,Meijer, Kerkhof, &Bogels (2010) suggested that there was a constructive correlation amidst the amount of sleep accumulated as well as their performance in learning institutions. The study was conducted among schoolchildren and adolescents where the children reported their comprehension of learning materials after variable phases of sleep time. This study was supported by Wittenboer (2000) who argued that period in bed, adequate rest at school and quality of sleep positively impacted on the functioning of the children. The study by Wittenboer (2000) however found no correlation between quality of sleep, time in bed and the concentration of children at school. Dewald et al (2010) performed a meta-analytical review of sleep and found out that there were different aspects between boys and girls aged between 8 to 18 years old in terms of the time of slept and performance in class. The sample size was 19,530, the sample was divided by sleep duration, sleep quality, sleepiness, and academic performance (Dewald et al., 2010). Somnolence recorded the strongest relation in association with academic performance with an r value of -0.1333 with sleep quality and sleep duration having a positive but weak association at r=0.096 and r=0.069 respectively. Overall, the study therefore asserted positive correlations between sleep duration and the ability to recall contents. Dewald et al (2010) however suggested that a longitudinal study was required to ensure the true and positive correlations were established. Consequently, findings by Dewald et al (2010) underlined the present study’s linkage of sleep and school performance. From the presented findings, it could be argued that quality sleep with minimal interruptions provides an elaborate environment for neurocognitive functioning of the brain due to elimination of disruptions that could interfere with overnight brain activities (Dewald et al., 2010) In an attempt to explain the concept of creativity Kaufman, Cole and Baer (2009) indicated that sleep was a core factor influencing how individuals tended to embrace creativity. Sleep was ranked as among the factors that influenced the creativity among people, and thus the quality and quantity of sleep was critical. Brand et al (2011) explored the association between dream recalls, perceived stress, sleep, gender, and creativity. The study found out that increased awakenings were associated with increased dream recalls. Besides, the low sleep quality was also associated low dream recalls. Stein (2014) further argued that there was some evidence of dream recalls being associated with personality traits like creativity. The study focused on 5580 adolescents where they answered questionnaires related to dreaming, perceived stress, sleep, and creativity. Females were better than male adolescents in terms of recalling their dreams as they felt a stronger impact of their dreams on their subsequent days (Garcia et al., 2014). The regression analysis showed that increased dream recalls were predicted by factors including gender, creativity, and sleep quality. Stein (2014) findings reiterated earlier studies by Brand et al (2011) that confirmed increased sleep quality, good moods, and levels of creativity affected dream recalls. This presents supporting evidence to the assumption that sleep quality affects the level of creativity.

In another study conducted by Pakpour, Moqaddam, Hosseiny, and Salimi (2016) on quality of sleep and its relation to the activity of the elderly, the results indicated that there were no significant relationship between the daily activities of the elderly and the quality and quantity of sleep. Pakpour et al., (2016) used Pittsburgh Sleep Quality Index (PSQI) to rate the responses and aid in analysis. The study employed face-to-face interview and filling of a questionnaire on daily activities of the participants while descriptive statistical analysis was conducted to find independent t-test, and correlation coefficient (Pakpour et al., 2016). From the PSQI, there were 7.5% of the respondents reported having poor sleep quality that was translated to less creativity showed in less activities attended by the elderly respondents. The study found out that increasing activity levels of the participants had a positive increase in their quality of sleep. Empirically, the level of creativity was measured by the ability of the participants to undertake activities of daily living (ADL) and instrumental activities of daily living (IADL) (Pakpour et al., 2016). From the findings, it can be deduced that the quality of sleep has an effect on the quality and amount of creativity. In another study by Burton et al. (2016), there were an indication that workplace based sleeping program had some significant effect on the performance of employees. Sleeping for a short time during work was also associated with increased efficiency and productivity among the workers (Schmitt, Belschak, & Den Hartog, 2016). The amount of sleep was also associated with the level of thinking after the sleep leading to more creativity and engagement among the individuals. Burton et al (2016) study correlated with the findings by Owens et al. (2012) and Stein (2014), which positively related quality of sleeping with enhanced creativity and performance. Regular of sleep, attention, and arousal of the mind to facilitate thinking is enhanced by having body rests and the concentration of brain activity that is refreshed during the sleep (Brain, 2000). From the literature available on the effects of sleep and creativity, there are contrasting conclusions that point towards the need for more studies. The present study was conducted to detect whether or not there is a correlation between sleep quality and creativity. The assumption is that there is going to be a constructive relationship amid sleep quality as well as creativity, which means that good quality of sleep will be related to more creativity.

Method

Participants

The participants were recruited by use of snowballing, and opportunity sampling methods. The participants were X individuals aged 18-30; the mean age was (SD=). The sample group included X females and Y males. The exclusion criteria included age group between 18-30 years old and the participants being English speakers. The study approached a large number of volunteers to complete the study, however, majority of potential participants were reluctant to join the sample population due to the longitudinal nature of the study.

Design

The study entailed repetition of measures design since participants were expected to complete all three tasks. Two variables were observed: sleep quality and Creativity while the Pittsburgh Sleep Quality Index (PSQI) was applied to measure sleep quality and sleep diary used for recording. Measurement of creativity was undertaken by use of the Guilford Alternative Uses Task. Nevertheless, to avoid confounding variables participants completed the creative task at the same period, in the morning.

Measures

The present study was based on 1 questionnaire which is The Pittsburgh Sleep Quality Index (PSQI), a sleep diary and a creativity task which is the Guilford Alternative Uses Task.

The Pittsburgh Sleep Quality Index (PSQI)

Sleep quality was examined using the PSQI (See appendix C). This questionnaire, is a self-report questionnaire that measures sleep quality through sleeping habits over the past month. The sleeping habits include subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleep medication, and daytime dysfunction (Buysse et al, 1989). The PSQI comprises of both open-ended questions and 0-3 Likert scale questions. The first 4 questions are open-ended while the rest of the questions are in form of 0-3 Likert scale questions. The scoring consists of four components: Originality, where answers given by lower number of participants are considerate more unusual and then get 2 points and those given by a large part of the sample are only given one point. Similarly, fluency is based on the amount of responses. Flexibility is considered by the different categories of the responses as answered by the participants while elaboration refers to the amount of detail included in the responses.

Sleep Diary

Guilford Alternative Uses Task The Guilford Alternative Uses Task measures the ability to produce as many uses for one common object as possible. However,

Procedure

Having gain ethical clearance from the ethical committee, emails inviting prospect participants to join the study were sent out as well as informal verbal contact by approaching potential known and unknown participants. Subsequently, an email containing the participant information sheet along with a consent form was sent to individual who positively agreed and were interested in taking part in the study. After signing the consent form, the participants of the study completed the PSQI. Consequently, after completing the PSQI questionnaire, the participants were asked to keep track of their sleeping pattern by filing a sleep diary for a week. After day 7, they were asked to complete a creative task. The creative task encompassed Guilford’s alternative uses task (GAU), where participants were asked to list as many as possible uses for a usual household item that was a newspaper and a brick for 5 min. The participants typed their answer on the computer since handwriting presented challenges to some participants who were suffering from dyslexia and similar conditions. The use of the computer for feeding data ensured neutrality and integrity of the data.

References

Ashworth, A., Hill, C. M., Karmiloff‐Smith, A., & Dimitriou, D. (2014). Sleep enhances memory consolidation in children. Journal of sleep research, 23(3), 304-310.

Brand, S., Beck, J., Kalak, N., Gerber, M., Kirov, R., Pühse, U., ... &Holsboer-Trachsler, E. (2011). Dream recall and its relationship to sleep, perceived stress, and creativity among adolescents. Journal of adolescent health, 49(5), 525-531.

Burton, W. N., Chen, C. Y., Li, X., McCluskey, M., Erickson, D., Barone, D., ... & Schultz, A.B. (2016). Evaluation of a Workplace-Based Sleep Education Program. Journal of Occupational and Environmental Medicine, 58(9), 911-917.

Buysse, D.J., Reynolds III, C.F., Monk, T.H., Berman, S.R., &Kupfer, D.J. (1989). The Pittsburgh Sleep Quality Index: A new instrument for psychiatric practice and research. Journal of Psychiatric Research, 28(2), 193-213.

Cai, D. J., Mednick, S. A., Harrison, E. M., Kanady, J. C., &Mednick, S. C. (2009). REM, not incubation, improves creativity by priming associative networks. Proceedings of the National Academy of Sciences, 106(25), 10130-10134.

Dewald, J. F., Meijer, A. M., Oort, F. J., Kerkhof, G. A., &Bögels, S. M. (2010). The influence of sleep quality, sleep duration and sleepiness on school performance in children and adolescents: a meta-analytic review. Sleep medicine reviews, 14(3), 179-189.

Garcia, C., Zhang, L., Holt, K., Hardeman, R., & Peterson, B. (2014). Latina adolescent sleep and mood: an ecological momentary assessment pilot study. Journal of Child and Adolescent Psychiatric Nursing, 27(3), 132-141.

Jung, C., Melanson, E., Frydendall, E., Perreault, L., Eckel, R. and Wright, K. (2010). Energy expenditure during sleep, sleep deprivation and sleep following sleep deprivation in adult humans. The Journal of Physiology, 589(1), pp.235-244.

Mello, M. T., Narciso, F. V., Tufik, S., Paiva, T., Spence, D. W., BaHammam, A. S., ... &Pandi-Perumal, S. R. (2013). Sleep disorders as a cause of motor vehicle collisions. International journal of preventive medicine, 4(3).

Owens, J., Gruber, R., Brown, T., Corkum, P., Cortese, S., O’Brien, L., ... & Weiss, M. (2013).Future research directions in sleep and ADHD: report of a consensus working group.Journal of attention disorders, 17(7), 550-564.

Pakpour, V., Moqaddam, M., Hosseiny, R. and Salimi, S. (2016). Quality of Sleep and Daily Activity of the Elderly in Zanjan. Journal of Research Development in Nursing and Midwifery, 13(1), pp.62-68.

Schmitt, A., Belschak, F. D., & Den Hartog, D. N. (2016). Feeling vital after a good night’s sleep: The interplay of energetic resources and self-efficacy for daily proactivity. Journal of occupational health psychology.

Steenari, M. R., Vuontela, V., Paavonen, E. J., Carlson, S., Fjällberg, M., &Aronen, E. T. (2003). Working memory and sleep in 6-to 13-year-old schoolchildren. Journal of the American Academy of Child & Adolescent Psychiatry, 42(1), 85-92.

Stickgold, R. and Walker, M. (2007). Sleep-dependent memory consolidation and reconsolidation. Sleep Medicine, 8(4), pp.331-343.

Wei, Y., Krishnan, G. and Bazhenov, M. (2016). Synaptic Mechanisms of Memory Consolidation during Sleep Slow Oscillations. Journal of Neuroscience, 36(15), pp.4231-4247.

Cai, D., Mednick, S., Harrison, E., Kanady, J. and Mednick, S. (2009). REM, not incubation, improves creativity by priming associative networks. Proceedings of the National Academy of Sciences, 106(25), pp.10130-10134.

Ritter, S., Strick, M., Bos, M., Van Baaren, R., & Dijksterhuis, A. (2012). Good morning creativity: Task reactivation during sleep enhances beneficial effect of sleep on creative performance. Journal of Sleep Research, 21(6), 643-647. doi: 10.1111/j.1365-2869.2012.01006.x

Lytle, L., Pasch, K. and Farbakhsh, K. (2010). The Relationship Between Sleep and Weight in a Sample of Adolescents. Obesity, 19(2), pp.324-331.