今天小编给大家带来了关于托福口语听力的知识点分享，通过每天一点点的努力，总会有好的收获，希望对大家的英语学习有所帮助，祝愿大家天天开心，生活愉快。

Didyoueverwonderwhyitisthatmostpeopleare"programmed"tosleepatnightinsteadofduringthedayIfthere'ssomethingaboutthecycleoflightanddarkthat'stellinguswhentosleep,thenshouldn'tthesleepcycleofablindpersonbedifferent

Asitturnsout,manyblindpeople—peoplewithnovisualperceptionoflightatall—dohavethesamesleepcycleassightedpeople.Sonowyou'rewondering,"Howcanthishappen"Theansweris:hormones,onehormoneinparticular.It'scalledmelatonin.Insightedpeople,thelevelofmelatoningoesupatnight,orwhenit'sdark,andgoesdownintheday,orwhenit'slight.It'sbelievedthatit'sthepresenceofthishormoneinthebloodthatgivesustheurgetosleep.Ifanincreaseinmelatoninlevel"programs"sightedpeopletosleepatnight,thenwhataboutblindpeople

Aresearcher,namedDr.CharlesCzeisler,tellsaboutaninterestingexperiment.Hetriedshiningabrightlightintotheeyesofsomeblindpeople.Whenhedidthis,henoticedthatthelevelofthemelatonininthebloodofthesesubjectswentdownjustasitwoulddoforsightedpeople.Somehow,theeyesofthesesubjects,eventhoughtheyweredamagedandhadnovisualperceptionoflight,couldtelltheirbrainwhentherewasmoreorlesslight.Now,thisdoesn'tworkforallblindpeople;infact,mostofCzeisler'ssubjectshadnohormonalresponsetolightatall.Furtherresearchmaybeabletoexplainthissensitivitytolightintermsofthetypeofblindnessofthesubject.

1.programme:v.编程，计划，安排

2.sighted:adj.看得见的，有视力的

3.hormone:n.［C］荷尔蒙，激素

4.melatonin:n.［C］退黑激素

5.urge:n.［C］强烈欲望

6.hormonal:adj.荷尔蒙的，激素的

7.intermsof:在方面