睡得不夠，狂飲咖啡也木有用

A new study found that after restricting sleep to 5 hours per night, caffeine use no longer improved alertness or performance after three nights.

一項新近研究表明，如果每天只睡5小時，那么3天后，咖啡因對于提神醒腦及工作績效完全沒有幫助。

Results show that relative to placebo, caffeine significantly improved Psychomotor Vigilance Task (PVT) performance during the first 2 days, but not the last 3 days of sleep restriction.

研究結果顯示，與安慰劑相比，咖啡因在前兩天能夠顯著提高精神運動警覺性作業(yè)(PVT)，而從第三天起便失效了。

"We were particularly surprised that the performance advantage conferred by two daily 200 mg doses of caffeine was lost after three nights of sleep restriction," said lead author Tracy Jill Doty, PhD, research scientist at Walter Reed Army Institute of Research. "These results are important, because caffeine is a stimulant widely used to counteract performance decline following periods of restricted sleep. The data from this study suggests that the same effective daily dose of caffeine is not sufficient to prevent performance decline over multiple days of restricted sleep."

該研究的第一作者、來自沃爾特里德陸軍研究院的Tracy Jill Doty博士表示：“在持續(xù)3天睡眠不足后，每日200毫克咖啡因攝入量帶來的績效幫助作用便消失了。我們對于這一結果感到非常驚訝?？Х纫虮粡V泛地用作睡眠不足后提神醒腦的神器，而本研究的結果表明，連續(xù)睡眠不足幾天后，咖啡因日常攝入量所帶來的奇效便不復存在。”

The research abstract was published recently in an online supplement of the journal Sleep and will be presented Monday, June 13 and Tuesday, June 14, in Denver at SLEEP 2016, the 30th Anniversary Meeting of the Associated Professional Sleep Societies LLC (APSS).

該研究的摘要近日發(fā)表于Sleep，在本月13、14日于美國丹佛召開的第30屆聯合專業(yè)睡眠學會(APSS)年會上，研究者對該研究進行了報告展示。

The study group consisted of 48 healthy individuals who participated in a double blind, placebo-controlled study. Sleep was restricted to five hours of time in bed for a total of five days. Participants were administered either 200 mg of caffeine or a placebo twice daily. A cognitive task battery was administered hourly during the wake periods and included a 10-minute PVT, Profile of Mood States (POMS), and the Stanford Sleepiness Scale (SSS). A modified Maintenance of Wakefulness Test (mMWT) was administered six times per day.

研究團隊征募了48名健康的參與者，參加了一項雙盲、安慰劑對照的實驗。研究者對每名參與者的睡眠時間進行控制：參與者首先確保連續(xù)5天10小時的充足睡眠，隨后連續(xù)5天內每天只能保證5小時的睡眠，最后3天內參與者每天擁有8小時睡眠時間。參與者被指定每日分配得到200毫克咖啡因，或者安慰劑。參與者還需要完成認知任務測驗，包括10分鐘精神運動警覺性作業(yè)(PVT)、情緒狀態(tài)量表(POMS)與斯坦福睡眠量表(SSS)，另外，每名參與者每6小時需進行1次改進的清醒度維持測試(mMWT)。