英语翻译yawning takes place when people are bored or sleepy and

英语翻译yawning takes place when people are bored or sleepy and serves the function of increasing alertness by reversing,through deeper breathing,the drop in blood oxygen levels that are caused by the shallow breathing that accompanies lack of sleep or boredom.Unfortunately,the few scientific investigations of yawning have failed to find any connection between how often someone yawns and how much sleep they have had or how tired they are.这一句话太长了..我把所有单词的意思都查了还是搞不懂意思,求高手给予标准的翻译.我暑假要去学的.