Project Report Title: Do sleeping qualities affect IQ?
As sleep is so important that we cannot live without, there must be some reasons. Research has proven that it is associated with many other aspects of our lives such as IQ and mood. It is a process to maintain the wellbeing of our internal functioning and an activity that we necessitate, not an option. The present research examined the effects of the quality of sleep people have on IQ. 100 individuals participated in the research and were asked to complete a sleep scale made by the researchers and an IQ test. The results signify that there was a significant positive correlation between one’s quality of sleep and how intelligent they are. There was also a surprise finding of a significant difference between genders, where the results for females was significant but not for males.
Why do we sleep? Every single creature on earth needs to spend time sleeping every day as a natural part of our lives; we spend on average a third of our lives sleeping. Many people decide however to spend less than the recommended time to accomplish certain tasks, there are many theories as to the exact reason why humans spend time sleeping although none of them ultimately conclusive. Investigation carried out by the National Science Foundation (1999-2004) showed that nearly 12% out of the 320 million American population suffer from different sleeping disorders. Moreover, 69% of children have reported having sleeping difficulties once or twice a week. In many cases when these symptoms occur, they are often being ignored and untreated (F. Dinges et al. 2005). In light of this we can see the ways in which sleep has an effect in many people’s lives, as well as the effects it can have on our external and internal environment. It is essential that we have good understanding of the importance of sleep, as factors such as having a higher IQ score is reflective variables such as better mood states, having the recommended hours of sleep and having a good sleeping quality. Recent research by Blackwell et al. (2014) has found that older men have developed an cognitive decline as they have an appalling quality of sleep. However, they have found no association between sleep duration and decline of the cognitive system. Even though it has no link between sleep duration and cognitive functioning, humans still need a certain amount of sleep everyday in order to have a good sleep quality. The following are some factors that will affect sleeping quality or being affected by the lack of sleep.
1. Using phones Using phone or any other electronic appliances before sleep might associate with bad sleeping quality as it can causes cognitive stimulation.(Adams et al. 2013) Just before you sleep, your brain’s electrical activity should start to decrease and neurons begin to slow down. However with the use of an electronic device, the opposite effect takes place; the light from electronic appliances such as your phone can prevent your body from resting. The light will essentially pass through the retina into the hypothalamus, making your body become tense thus causing a production of the stress hormone cortisol. As a result the body’s “fight or flight” response would occur. Thus delaying the secretion of the sleep-inducing hormone, melatonin, ultimately leading to a bad sleeping quality.
2.Mood Throughout the day many of us experience events or situations that can ultimately affect our mood. However if someone is experiencing a bad or low mood it can be found there is an association between this variable and sleeping quality. Some researchers have found relationships between the mood of an individual and the quality of sleep they receive. (Zawadzki et al. 2013) They found that people who have certain emotion disorders such as depression or anxiety are at a higher risk of developing certain disorder such as insomnia, which ultimately decreases one’s sleeping quality. Research by Meltzer, L. J., & Mindell, J. A. (2007) has also proved that people with sleeping disorders are likely to have mood disorders and stress related illnesses too; it is found that having difficulty in and lack of sleeping are normally the first symptoms and a great risk factor when a mood disorder first develops.
3. Hours of sleep
The amount of sleep one receives ultimately varies among different age groups. There was a study in 2005 by Ursin et al. that showed how the amount of sleep people received varied across populations. There were 3531 males and 5329 females, a total of 8860 participants, age ranged from 40 to 45. Participants were from Bergen and other four communities. They found that people with different work shifts, place of living education and marital status have variations in sleep duration. It was genuinely suggested that an adult should have at least 7 to 8 hours sleep a day. If taken from a biological perspective, it was also proposed that there were certain traits to indentify within genes that provide a predictor of on average how much sleep one is likely to engage in.
With regards to previous research the goal of our study was to investigate whether sleep quality has an effect on IQ. This was a correlation study using 100 participants and our predictive hypothesis would be that the quality of sleep people receive does in fact have an association with IQ levels.
Method Participants For this research, a sample of 100 participants (57 Females and43 Males) aged 18 or above were selected(M=23.56,SD=6.08) and obtained through opportunity sampling which included Psychology Undergraduates from University of Warwick as well as their families and friends. Their participation in the study was voluntary and they were not paid for their participation. Design This was a correlation study. This was a within subject design under self-report condition. The independent variable for this research would be the sleeping quality (mood, hours of sleep and use of electronic devices) of the participants which was being measured through a sleep scale. The dependent variable was the participants’ IQ , that they would scored on in IQ test given after completing their sleeping scale. Material A Sleeping Quality Scale which was developed by the researchers, driven by the formed hypothesis and literature reviewed. The scale consisted of 7 questions and an IQ test of 30 questions which was found on (www.iqtest.com). Please refer to Figure 1 for the sleeping quality scale used. The questions in the IQ test were generated through the following aspects: General knowledge, solving problems through mathematics, logic and analogy. The Brief Mood Introspection Scale by John D. Mayer was also used in the research, using these symbols ‘ XX,X,V,VV’ to indicate their mood state.
Procedure Firstly, participants were informed of the procedure, were given a consent form and asked to sign and write their require contact details. They were then given a short semi-structured questionnaire (the sleeping quality scale) which stated “Please put a tick in the box which suits you the most” at the beginning of the page. The questionnaire consisted of seven questions about their sleeping quality such as the amount of sleep they have every night and the amount of time they took to fall asleep. They were also asked about their use of electronic devices, the number of electronic devices they own, hours spent on electronic devices as well as the hours spent each week using one at their place of employment. A Brief Mood Introspection Scale was given afterwards, there were two groups of adjectives about mood which were in positive and negative aspects, XX, X, V, and VV were used to indicate their mood. If they definitely did not feel that particular mood at that moment they would select “XX” and select “X” if they do not feel in that mood. Similarly, if they feel that particular mood slightly, they would select “V” and they would select ‘VV’ if they were definitely in that specific mood. After completing both of the scales, they were given an IQ test which contained 30 questions. In each question there was a statement, the participants had to indicate whether it was true or false. They were asked to complete the scales and the IQ test in silence and were given as much time as they needed to complete both. The participant’s identity was left as anonymous. The Sleeping quality Scale was marked out of 142 (M=110.75,SD=13.75) and the IQ test was marked out of 150 (M=91.08,SD=12.64). If a participant was to score (142) on the sleep quality questionnaire, the sleep scale would determine that they have high sleep quality and therefore a score of 0 would determine a low sleep quality as 142 is the maximum score that can be obtained. Correspondingly, if a participant was to score (150) in the IQ test would determine they are highly intelligent. The higher they got in the IQ test, the higher their level of intelligence. After the study was completed, participants were debriefed of the aims of the study and thanked for their time.
Please refer to Table 1 for all the means and standard deviations of the sleeping scale and the IQ test.
Our hypothesis was that the score of the sleeping quality scale participants would positively correlate with their IQ test score and was successfully proved by our results. There was nothing major went wrong in the conduct of the study. When examining the effects of sleeping quality on IQ, researchers created a sleep questionnaire and an IQ test found online. The dependent variable was the score participants gained in the IQ test. In the IQ test, participants will be awarded 5 marks for each question that they have answered correctly. There were 30 questions, so the highest they could get was 150. We used the scores they got from the IQ test to determine how intelligent they were. The Sleep Scale consisted of 7 questions and was marked out of 142. The higher they scored on the Sleep Scale, the better sleep quality they have. Referring to results Table 1, participants’ mean IQ score was above national average (M=110.75, SD=13.75) and their scores from the sleeping scale was relatively high (M=91.08,SD=12.65). However, when looking at the genders separately from Table 3 & Table 4, females (M=109.91, SD=13.61) was slightly less intelligent than males (M=111.86, SD=14.02) based on their performance on this IQ test; males also show slightly better quality of sleep (M=92.42,SD=11.67) than females (M=90.07,SD=13.35). Pearson Correlation test had surprisingly shown that females had a significant result r(57)=.306,p<.05, whereas males had not, r(43)=.205, p>.05. This corresponded to sleep quality does have an effect on females’ IQ score while for male, the two factors do not associate with each other. Overall, it was found that sleep quality was positively correlated with IQ score gained, r(100)=.269, p<.05. Please refer to Figure 1, Figure2 &Figure 3 for the graphs of the correlation between participants’ scores of the sleep scale and their IQ.
Table 1 Means and standard deviations of measures taken.
Zero-order correlations among measures taken.
Note – N = 100. Correlations are controlling for other variable.
Figure 1. The correlation between the scores participants gets in the sleeping scale and their IQ.
Figure 2. The correlation between the scores females gets in the sleeping scale and their IQ.
Table 3. Means and standard deviations of measures taken (female).
Table 5. Zero-order correlation among measures taken (female).
Figure 3. The correlation between the scores males gets in the sleeping scale and their IQ.
Table 4. Means and standard deviations of measures taken (male).
Table 6. Zero-order correlation among measures taken (male).
Discussion Our hypothesis was that sleeping quality does have an association with IQ test performance. The predicted hypothesis was supported by the results obtained. However there is divergence exists in the gender. It has always been suggested that there is a link between sleep quality and cognitive functioning and IQ. Not only does the outside elements that might affect our quality of sleep but also the inside elements that we cannot ignore. The time participants took the test also has an impact on the score they gained, besides, it has been purposed that IQ does change over life span. Barter, E. A. (1997).
Recent research from Gruber et al. (2013) has found out that sleep quality does have an effect on children’s IQ measures, however the underlying mechanism stay unidentified. They found that when the frequency of the sleep spindle was lower, it was associated with better performance on WISC-IV scales (a working memory scale) So, when considering the environment that affects our sleep quality, we should also consider the biological aspects (e.g. the sleep spindle). Gruber et al. (2013) conducted a research to investigate whether sleep quality does have an effect on children’s IQ performances. They hypothesised that sleep spindles frequencies, amplitude and duration would be associate with the performance on perceptual reasoning, verbal comprehension and working memory. However, after completing the study, they found that although there was an association between sleep spindle frequency and better performance on the perceptual reason and working memory but not with the performance of the IQ test.
Also, as sleep is such an essential part of our lives, government and companies should purpose more policies that encourage and ensure their citizens to have more sleep. Research from Kyle Stanyar (2012) has proved that high workload, lengthy shift work and work weeks has an association with poor sleep quality. Therefore, government should not just place emphasize on school children but also working adults.
The research stresses the importance of the quality of sleep to IQ. Significance difference were indicated in the results, the quality of sleep does affect IQ in Females. This might be because of the biological difference in genders that researchers might consider when replicating this research.
Adams et al. adolescent Sleep and cellular Phone Use: recent trends and implications for research. Health Services Insights 2013:6 99–103
American Academy of Sleep Medicine. (2014, March 31). Poor sleep quality linked to cognitive decline in older men. ScienceDaily. Retrieved May 5, 2014 from www.sciencedaily.com/releases/2014/03/140331170557.htm
Barter, E. A. (1997). Stability and change in IQ scores: An eleven-year study in children ages 6-17. (Order No. 1384630, California State University, Fullerton). ProQuest Dissertations and Theses, , 77-77 p. Retrieved from http://0-search.proquest.com.pugwash.lib.warwick.ac.uk/docview/304428718?accountid=14888. (304428718).
Dewald, J. F., Meijer, A. M., Oort, F. J., Kerkhof, G. A., & Bogels, 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, 179-189. doi:http://dx.doi.org/10.1016/j.smrv.2009.10.004
Epstein, L. J. (2008) Sleep and mood. Retrieved on 4/5/14 from http://healthysleep.med.harvard.edu/need-sleep/whats-in-it-for-you/mood.
Gruber, R., Wise, M. S., Frenette, S., Knaauper, B., Boom, A., Fontil, L., & Carrier, J. (2013). The association between sleep spindles and IQ in healthy school-age children. International Journal of Psychophysiology, 89, 229-240.
Gruber, R., Laviolette, R., Deluca, P., Monson, E., Cornish, K., & Carrier, J. (2010). Short sleep duration is associated with poor performance on IQ measures in healthy school-age children. Sleep Medicine, 11, 289-294.
Hatfield,H. (2008). Power down for better sleep. Retrieved on 4/5/14 from http://www.webmd.com/sleep-disorders/features/power-down-better-sleep.
Kong, F., Li, Q., & Liu, S. (2011). Poor sleep quality predicts decreased cognitive function independently of chronic mountain sickness score in young soldiers with polycythemia stationed in tibet. High Altitude Medicine & Biology, 12, 237-242.
Meltzer, L. J., & Mindell, J. A. (2007). Relationship between child sleep disturbances and maternal sleep, mood, and parenting stress: A pilot study. Journal of Family Psychology, 21, 67-73.
Ursin R; Bjorvatn B; Holsten F et al. Sleep duration, subjective sleep need, and sleep habits of 40- to 45-year-olds in the Hordaland health study. SLEEP 2005;28: 1260-1269.
Zawadzki, M. J., Graham, J. E., & Gerin, W. (2013). Rumination and anxiety mediate the effect of loneliness on depressed mood and sleep quality in college students. Health Psychology, 32, 212-222.