Sleeping Helps you Lose!

Researchers from the University of Chicago and the University of Wisconsin, Madison, recently reported new findings on the relationship between sleep and weight loss. In a clinical randomized trial, subjects getting 5.5 hours of sleep over a 2-week period lost the same amount of weight as their counterparts getting 8.5 hours of sleep. But subjects on the low-sleep regimen lost significantly more lean muscle and significantly less body fat than did subjects on the long-sleep regimen. Stinting on sleep, therefore, may counteract other weight-loss measures such as restricting calories and/or exercising.

The study examined sleep and weight loss in 10 overweight, non-smoking individuals (3 women and 7 men). Subjects were randomly assigned to two treatments: 8.5 hours of sleep or 5.5 hours of sleep. All subjects were given the same moderately restricted diet and studied for two 2-week periods in a sleep laboratory. Food, drink, and exercise were controlled. Investigators measured fat loss and fat-free body mass as well as several physiological variables related to how the body uses energy.

1. From the summary please identify the following:

a. The question being asked or hypothesis being tested

b. The controls used

c. The independent variable

d. The dependent variable and how it is measured

e. Conclusions reached by authors

2. What is the sample size?  Does the size of the sample influence the confidence you have in the results of the study?  Explain.  Do any of the other features of the study design reduce your confidence in the results?  Explain.

Does the study report a correlation, a causal relationship, or both?  If it’s a correlation and not a causal relationship, offer at least one explanation for the correlation other than the effects of sleep itself.

QUESTION:

1. Name and describe the mechanisms required for a cell to obtain all the different kinds of molecules that it needs. (Hint: mechanisms for transporting materials across cell membrane)