Passage
Across the lifespan, mental and physical health depends on adequate sleep. Extensive research suggests that sleep needs and characteristics change throughout an individual's life (Figure 1) .
Figure 1 Average hours of rapid eye movement (REM) and non-REM sleep for different age groups across the lifespanChronic sleep deprivation acts as a physiological stressor and can have a multitude of short- and long-term negative health consequences. Studies show that over 30% of adults get less than the recommended minimum of 7 hours of sleep per night, putting them at greater risk for metabolic disorders (eg, obesity, diabetes) , cardiovascular disease (eg, high blood pressure, stroke) , and emotional disorders (eg, anxiety, depression) . Sleep deprivation is also associated with impaired cognitive functioning, decreased work performance, and an increased risk of accidents.However, the guideline that adults sleep at least 7 hours per night does not account for the considerable variation in individual sleep needs. Research suggests that some individuals, known as "long sleepers," require an average daily sleep duration of more than 9 hours, while "short sleepers" require an average daily sleep duration of less than 6 hours. One study found that biological night duration (established by one's circadian pacemaker or "master clock") appears to be a few hours shorter for short sleepers as compared to long sleepers. Other studies suggest that short sleepers regularly sleep less than 7 hours without any apparent negative consequences due to one or more genetic mutations, such as a mutation on the DEC2 gene (also known as BHLHE41) , which codes for a transcription factor involved in regulating circadian rhythms.
-What type of study design is most appropriate to investigate whether the number of hours slept per night predicts the number of health care provider visits for those with and without the DEC2 gene mutation?

Question

Passage
Across the lifespan, mental and physical health depends on adequate sleep. Extensive research suggests that sleep needs and characteristics change throughout an individual's life (Figure 1) .

Figure 1 Average hours of rapid eye movement (REM) and non-REM sleep for different age groups across the lifespanChronic sleep deprivation acts as a physiological stressor and can have a multitude of short- and long-term negative health consequences. Studies show that over 30% of adults get less than the recommended minimum of 7 hours of sleep per night, putting them at greater risk for metabolic disorders (eg, obesity, diabetes) , cardiovascular disease (eg, high blood pressure, stroke) , and emotional disorders (eg, anxiety, depression) . Sleep deprivation is also associated with impaired cognitive functioning, decreased work performance, and an increased risk of accidents.However, the guideline that adults sleep at least 7 hours per night does not account for the considerable variation in individual sleep needs. Research suggests that some individuals, known as "long sleepers," require an average daily sleep duration of more than 9 hours, while "short sleepers" require an average daily sleep duration of less than 6 hours. One study found that biological night duration (established by one's circadian pacemaker or "master clock") appears to be a few hours shorter for short sleepers as compared to long sleepers. Other studies suggest that short sleepers regularly sleep less than 7 hours without any apparent negative consequences due to one or more genetic mutations, such as a mutation on the DEC2 gene (also known as BHLHE41) , which codes for a transcription factor involved in regulating circadian rhythms.
-What type of study design is most appropriate to investigate whether the number of hours slept per night predicts the number of health care provider visits for those with and without the DEC2 gene mutation?

Quizplus · Accepted Answer

11ecba2d_0c5b_a514_a3bf_4726d9499245_MD0008_00 Longitudinal studies involve collecting data over a period of time. Longitudinal studies, which can be either experimental (in which a variable is manipulated) or observational, are useful for measuring how variables change over time. If a researcher wants to investigate whether the number of hours slept per night predicts the number of health care provider visits in those with and without the DEC2 gene mutation, the researcher would need to collect data over a period of time (ie, longitudinally). More specifically, the researcher would perform an observational longitudinal study. Observational studies are conducted when it is unethical or unfeasible to manipulate a variable of interest. (Choice A) Ethnographic studies use observation and interview to qualitatively study people within their own communities and provide descriptive information about their cultures, behaviors, norms, and values. An investigation of whether the number of hours slept per night predicts the number of health care provider visits is more quantitative in nature, so an ethnographic design would not be appropriate. (Choice B) A cross-sectional study is an observational study that measures a variable in a population or subpopulation at one time point. Because this example requires measuring hours slept per night and health care provider visits over time, this would not be an appropriate study design. (Choice D) A randomized controlled trial randomly sorts subjects into treatment and control groups. In this example, researchers cannot manipulate a DEC2 gene mutation in humans, so it is not possible to assign people randomly to one of the two study groups. Educational objective: A longitudinal study is used to investigate a variable of interest within a sample population over a period of time. An observational longitudinal study is performed when it is unethical or unfeasible to manipulate the variable of interest.

Passage Across the Lifespan, Mental and Physical Health Depends on Adequate