Dehydration causes blood volume to drop , researchers say , resulting in less blood and oxygen flow to the brain and dilated blood vessels .
研究人员称,脱水导致血容量下降之后,供给大脑的血液和氧气就会减少,血管就会膨胀。
Subsequent research found that the pupils of intelligent people ( as defined by their sat scores ) dilated less in response to cognitive tasks compared to those of less intelligent participants , indicating a more efficient use of brainpower .