Late-NightDrinking
Coffeeloversbeware.Havingaquickpick-me-upcupofcoffeelateinthedaywillinterruptyoursleep.Aswellasbeingastimulant,caffeineinterruptstheflowofmelatonin,thebrainhormonethatsendspeopleintoasleep.
Melatoninlevelsnormallystarttoriseabouttwohoursbeforebedtime.Levelsthenpeakbetween2amand4am,beforefallingagain.Ittheneurohormonethatcontrolsoursleepandtellsourbodywhentosleepandwhentowake,saysMauriceOhayonoftheStanfordSleepEpidemiologyResearchCenteratStanfordUniversityinCaliforniA.ButresearchersinIsraelhavefoundthatcaffeinatedcoffeehalvesthebodylevelsofthissleephormone.
LotanShiloandateamattheSapirMedicalCenterinTelAvivUniversityfoundthatsixvolunteerssleptlesswellafteracupofcaffeinatedcoffeethanafterdrinkingthesameamountofdecal.Onaverage,subjectsslept336minutespernightafterdrinkingcaffeinatedcoffee,comparedwith415minutesafterdecal.Theyalsotookhalfanhourtodropoff,twiceaslongasusual.
Inthesecondphaseoftheexperiment,theresearcherswokethevolunteerseverythreehoursandaskedthemtogiveaurinesample.Shilomeasuredconcentrationsofabreakdownproductofmelatonin.Theresultssuggestthatmelatoninconcentrationsincaffeinedrinkerswerehalfthoseindecaldrinkers.InapaperacceptedforpublicationinSleepMedicine,theresearcherssuggestthatcaffeineblocksproductionoftheenzymethatdrivesmelatoninproduction.
Becauseitcantakemanyhourstoeliminatecaffeinefromthebody,Ohayonrecommendsthatcoffeeloversswitchtodecafafterlunch.
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