A vivid example of such replay can be seen in a video researchers made recently about sleep disorders.

研究人员最近制作了一段关于睡眠障碍的视频，从中可以看到一个生动的例子。

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The body can not make tryptophan and a lack of this amino acid can result in sleep disorders which lead to higher levels of anxiety and stress.

人体不能合成色氨酸，而这种氨基酸的缺乏会导致睡眠失调，引发更严重的紧张和焦虑。

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Stimulus Control Therapy Professor Richard R. Bootzin has been researching sleep disorders for many years at the University of Arizona sleep research Lab.

多年来，美国亚利桑那州睡眠研究实验室刺激控制疗法方面的理查德·布特森教授一直在研究睡眠障碍现象。

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Professor John Stradling, of the Oxford Centre for Sleep Medicine said these kind of sleep disorders were very rare.

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"Exercisers fall asleep faster, suffer fewer middle-of-the-night wake-ups and have a reduced risk of sleep disorders, " says study co-author Brad Cardinal, co-director of the sport and exercise psychology program at Oregon State University.

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Crash factors may include sleep loss, driving patterns -- early morning or late at night, for example, use of sedating medications, untreated or unrecognized sleep disorders, or consumption of alcohol.

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