How much sleep does a person need?【31】the physiological bases of the need for sleep remain
【36】consistently has been associated with the varying amount, quality, and pattern of electrophysiologically defined sleep. The newborn infant may spend an average of about 16 hours of each 24-hour period in sleep,【37】the sleep time drops sharply; by two years of age, it may【38】from nine to 12 hours. Decreases to approximately six hours have been observed among the elderly.
【39】will be discussed from below, EEG sleep studies have indicated that sleep can be considered to consist of several different stages. Developmental changes in the relative proportion of sleep time【40】in these sleep stages are as striking as age-related changes in total sleep time.
(31)
A.As
B.Despite
C.While
D.Whether
C
解析:做完形填空题往往需要“瞻前顾后”才能做出判断。本题必须要将句子下文看完才能确定答案。后面的much evidence has been gathered on how much sleep people do in fact obtain与前面提到的“睡眠心理基础并不明确”意思对立,因此选择含有“对比,让步”意思的连词while合理。despite虽然也能表达让步关系,却是介词,不能引导从句。