Sleep and Grades AAQ

Your response to the question should be provided in six parts: A, B, C, D, E, and F. Write the response to each part of the question in complete sentences. Use appropriate psychological terminology in your response.

Using the source provided, respond to all parts of the question.
A. Identify the research method used in the study.
B. State the operational definition of sleep quality.
C. Describe what the researchers  meant when they stated that the correlation between mean sleep duration and overall score was significant. 
D. Identify at least one ethical guideline applied by the researchers.
E. Explain the extent to which the research findings may or may not be generalizable using specific and relevant evidence from the study.
F. Explain how at least one of the research findings supports or refutes the researchers’ hypothesis that adequate, consistent, & quality sleep positively affects academic performance. 

Introduction
Although numerous studies have investigated the relationship between sleep and students’ academic performance, these studies utilized subjective measures of sleep duration and/or quality, typically in the form of self-report surveys; very few to date have used objective measures to quantify sleep duration and quality in students. Our aim in this study was to explore how sleep affects university students’ academic performance by objectively and ecologically tracking their sleep throughout an entire semester By collecting quantitative sleep data over the course of the semester on nearly 100 students, we aimed to relate objective measures of sleep duration, quality, and consistency to academic performance from test to test and overall in the context of a real, large university college course. A secondary aim was to understand gender differences in sleep and academic performance.
Participants
One hundred volunteers (47 females) were selected from a subset of students who volunteered among 370 students enrolled in Introduction to Solid State Chemistry at the Massachusetts Institute of Technology to participate in the study. Participants were informed of the study and gave written consent obtained in accordance with the guidelines of and approved by the MIT Committee on the Use of Humans as Experimental Subjects. Due to limitations in funding, we only had access to 100 Fitbit devices and could not enroll all students who volunteered; consequently, the first 100 participants to volunteer were selected. Seven participants were excluded from analysis because they failed to wear their activity tracker for more than 80% of the semester, three participants were excluded because they lost their wearable activity tracker, and another two participants were excluded because they completed less than 75% of the assessments in the class. Of the 88 participants who completed the study (45 females), 85 were freshmen, one was a junior and two were seniors (mean age = 18.19 years).
Method
Participants were asked to wear an activity tracker (Fitbit Charge HR) for the entire duration of the semester without going below 80% usage each week.  The Fitbits allowed for multiple sleep measures, including sleep duration and quality for every instance of sleep throughout the day, to be correlated with in-class performance on quizzes and midterm examinations. Sleep quality was determined using Fitbit’s proprietary algorithm that produces a value from 0 (poor quality) to 10 (good quality). Nine quizzes, three midterm examinations, and one final examination were administered throughout the 14-week class to assess the students’ academic achievement. We calculated for each student an overall score defined as the sum of the eight quizzes and three midterms to summarize academic performance in the course.
Results and Discussions
Bedtime and wake-up times
On average, students went to bed at 1:54 a.m. (Median = 1:47 a.m., Standard Deviation (SD) of all bedtime samples = 2 h 11 min, SD of mean bedtime per participant = 1 h) and woke up at 9:17 a.m. (Median = 9:12 a.m., SD of all wake-up time samples = 2 h 2 min; SD of mean wake-up time per participant = 54 min). We conducted an ANOVA with the
overall score (sum of all grade-relevant quizzes and exams) as the dependent variable and bedtime (before or
after median) and wake-up time (before or after median) as the independent variables.  We found a main effect of bedtime (F (1,82) = 6.45, p = 0.01), such that participants who went to bed before median bedtime had significantly higher overall score (X =77.25%, SD = 13.71%) compared with participants who went to bed after median bedtime (X = 70.68%, SD = 11.01%). We also found a main effect of wake-up time (F (1, 82) = 6.43, p = 0.01), such that participants who woke up before median wake-up time had significantly higher overall score (X = 78.28%, SD = 9.33%) compared with participants who woke up after median wake-up time (X = 69.63%, SD = 14.38%).
A Pearson’s product-moment correlation between average bedtime and overall score revealed a significant and negative correlation (r (86) = −0.45, p < 0.0001), such that earlier average bedtime was associated with a higher overall score. There was a significant and negative correlation between average wake-up time and overall score (r (86) = −0.35, p < 0.001), such that earlier average wake-up time was associated with a higher overall score.
Sleep duration, quality, and consistency in relation to academic performance
Overall, the mean duration of sleep for participants throughout the entire semester was 7 h 8 min (SD of all sleep samples = 1 h 48 min, SD of mean sleep duration per participant = 41 min). There was a significant positive correlation between mean sleep duration throughout the semester (sleep duration) and overall score (r (86) = 0.38, p < 0.0005), indicating that a greater amount of sleep was associated with a higher overall score (Fig. 1a).
Similarly, there was a significant positive correlation between mean sleep quality throughout the semester (Sleep Quality) and Overall Score (r (86) = 0.44, p < 0.00005). Sleep inconsistency was defined for each participant as the standard deviation of the participant’s daily sleep duration in minutes so that a larger standard deviation indicated greater sleep inconsistency. There was a significant negative correlation between sleep inconsistency and overall score (r (86) = −0.36, p < 0.001), indicating that the greater inconsistency in sleep duration was associated with a lower overall score (Fig. 1b).

Timing of sleep
Night before assessments. We conducted a correlation between sleep quality the night before a midterm and respective midterm scores as well as sleep duration the night before a midterm and respective scores. There were no significant correlations with sleep duration or sleep quality for all three midterms (all rs < 0.20, all ps> 0.05). Similar analyses for sleep duration and sleep quality the night before respective quizzes revealed no correlations (rs from 0.01 to 0.26, all ps > 0.05).
Week and month leading up to assessments. To understand the effect of sleep across the time period while course content was learned for an assessment, we examined average sleep measures during the 1 month leading up to the midterms. We found a significant positive correlation between average sleep duration over the month leading up to scores on each midterm (rs from 0.25 to 0.34, all ps < 0.02). Similar analyses for average sleep duration over one week leading up to respective quizzes were largely consistent with those of midterms, with significant correlations on 3 of 8 quizzes (rs from 0.3 to 0.4, all ps < 0.05) and marginal correlations on an additional 3 quizzes (rs from 0.25 to 0.27, all ps < 0.08). There was a significant and positive correlation between sleep quality scores averaged over the month leading up to each midterm for all three midterms (rs from 0.21 to 0.38, all ps < 0.05). Similar analyses for average Sleep Quality over one week leading up to respective quizzes revealed a significant correlation on 1 of 8 quizzes (r (86) = 0.42, p < 0.005) and marginal correlations on 3 quizzes (rs from 0.25 to 0.27, all ps < 0.08).
Gender Differences
Females had better Sleep Quality (t (88) = 2.63, p = 0.01), and less sleep inconsistency (t (88) = 2.18, p = 0.03) throughout the semester compared with males, but the two groups experienced no significant difference in sleep duration (t (88) = 1.03, p = 0.3). Sleep duration and sleep quality were significantly correlated in both males (r (41) = 0.85, p < 0.00001) and females (r (43) = 0.64, p< 0.00001), but this correlation was stronger in males (Z = −2.25, p = 0.02) suggesting that it may be more important for males to get a long-duration sleep in order to get good quality sleep. In addition, sleep inconsistency and sleep quality were significantly negatively correlated in males (r (41) = −0.51, p = 0.0005) but not in females (r (43) = 0.29, p > 0.05), suggesting that it may be more important for males to stick to a regular daily sleep schedule in order to get good quality sleep. Females scored higher on overall score compared with males (t (88) = −2.48, p = 0.01), but a one-way analysis of covariance (ANCOVA) revealed that females and males did not perform significantly different on overall score when controlling for Sleep Quality, F (1, 85) = 2.22, p = 0.14. Sleep inconsistency and overall score were negatively correlated in males (r (41) = −0.44, p =0.003) but not in females (r (43) = −0.13, p = 0.39), suggesting that it is important for males to stick to a regular sleep schedule in order to perform well in academic performance but less so for females. No other gender differences were detected between other sleep measures and overall score.

This study found that longer sleep duration, better sleep quality, and greater sleep consistency were associated with better academic performance. A multiple linear regression revealed that these three sleep measures accounted for 24.44% of the variance in overall grade performance.  The present study also provides new insights about the timing of the relation between sleep and academic performance. We did not find that sleep duration the night before an exam was associated with better test performance. Instead we found that both longer sleep duration and better sleep quality over the full month before a midterm were more associated with better test performance.