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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.
-For the study comparing long sleepers to short sleepers described in the final paragraph, researchers were LEAST likely to have measured which of the following biomarkers?

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.
-For the study comparing long sleepers to short sleepers described in the final paragraph, researchers were LEAST likely to have measured which of the following biomarkers?

Quizplus · Accepted Answer

11ecba2d_0c56_c30f_a3bf_491fa4db7ac3_MD0008_00 Circadian rhythms, which are regulated endogenously by a circadian pacemaker (master clock), are cycles in physiological activity (eg, hormone release) that occur over 24-hour intervals. Most circadian rhythms occur in accordance with the timing of the sleep/wake cycle because they are synchronized through the synthesis and secretion of melatonin from the pineal gland, a light-dependent process. A biomarker is a measurable indictor of a biological phenomenon. To compare differences in the circadian clocks of long sleepers and short sleepers, researchers must measure biomarkers that generally follow a 24-hour cycle of activity, such as: Core body temperature, which fluctuates between 38°C (in the daytime) and 36°C (just before waking) Plasma melatonin level, which peaks during sleep but remains relatively low during waking hours Cortisol, which under normal conditions peaks immediately after waking and is lowest just before sleep Oxytocin, a hormone produced by the hypothalamus and released by the pituitary gland, is involved in pair bonding, reproductive behavior, labor, and lactation. Oxytocin release is not strongly associated with the sleep/wake cycle, so researchers would be least likely to have used this biomarker as a measure of circadian rhythms. (Choices A, B, and D) Core body temperature, melatonin, and cortisol are three biomarkers that researchers would have potentially measured to compare the circadian clocks of long sleepers to those of short sleepers. Educational objective: Melatonin, a hormone released from the pineal gland when light levels are low, synchronizes the internal circadian clock according to daylight. The circadian clock regulates circadian rhythms (physiological processes fluctuating around a 24-hour cycle), including core body temperature and plasma cortisol levels.

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