单选题
As it is, sleep is so undervalued that getting by on fewer hours has become a badge of honor. Plus, we live in a culture that 26 to the late-nighter, from 24-hour grocery stores to online shopping sites that never close. It's no surprise, then, that more than half of American adults don't get the 7 to 9 hours of shut-eye every night as 27 by sleep experts. Whether or not we can catch up on sleep—on the weekend, say—is a hotly 28 topic among sleep researchers. The latest evidence suggests that while it isn't 29 , it might help. When Liu, the UCLA sleep researcher and professor of medicine, brought 30 sleep-restricted people into the lab for a weekend of sleep during which they logged about 10 hours per night, they showed 31 in the ability of insulin (胰岛素) to process blood sugar. That suggests that catch-up sleep may undo some but not all of the damage that sleep 32 causes, which is encouraging, given how many adults don't get the hours they need each night. Still, Liu isn't 33 to endorse the habit of sleeping less and making up for it later. Sleeping pills, while helpful for some, are not 34 an effective remedy either. 'A sleeping pill will 35 one area of the brain, but there's never going to be a perfect sleeping pill, because you couldn't really replicate (复制) the different chemicals moving in and out of different parts of the brain to go through the different stages of sleep,' says Dr. Nancy Collop, director of the Emory University Sleep Center. A. alternatively F. ideal K. presumption B. caters G. improvements L. ready C. chronically H. necessarily M. recommended D. debated I. negotiated N. surpasses E. deprivation J. pierce O. target