Ask readers of this newspaper if they're getting adequate sleep, and many would probably say 'Ha!'

    Twenty percent of Americans sleep less than six hours a night, and nearly one-third have lost sleep worrying about financial concerns, according to the National Sleep Foundation, which recommends that adults get seven to nine hours. 'Our society thinks sleep is for slackers -- or suckers,' says Darrel Drobnich, the organization's chief program officer.

    But all that lost sleep is taking an insidious toll. Chronic, inadequate sleep raises the risk of cardiovascular disease, depression, diabetes and obesity. It impairs cognitive function, memory and the immune system and causes more than 100,000 motor-vehicle accidents a year. Sleep deprivation also changes the body's metabolism, making people eat more and feel less satisfied.

    Studies presented at the American Association of Sleep Medicine's annual meeting in Seattle recently also found that inadequate sleep is associated with lower GPAs among college students and with elevated levels of visfatin, a hormone secreted by belly fat that is associated with insulin resistance.

    What many people don't realize is that even if they log respectable time in bed （known as TIB among sleep researchers）, they may be getting poor-quality sleep, with not enough of the restorative phases. REM, the Rapid Eye Movement phase in which dreaming occurs, is crucial for consolidating memories, learning, creativity, problem-solving and emotional balance. Deep, or slow-wave sleep, when the body secretes human growth hormone, is critical for development and physical repair. Both REM and deep sleep decline with age and are highly vulnerable to disruptions, from caffeine and alcohol to anxiety and a variety of sleep disorders.

    One tip-off that you haven't gotten enough restorative sleep is trouble waking up and excessive daytime sleepiness （a condition known as EDS）. 'People say, 'Oh, I don't have a sleep problem. I can fall asleep anywhere, anytime' -- but that means you are excessively sleepy,' says Charles Czeisler, a professor of sleep medicine at Harvard Medical School.

    Other symptoms of sleep deprivation include mood changes, difficulty focusing or remembering and a chronic need for caffeine, which can then create a vicious circle of dependence and disruption. That would be me.

    Finding out what's going on in your sleep generally requires spending the night in a professional sleep lab hooked up to lots of wires and monitors. But I've been testing a new home-sleep monitor called the Zeo Personal Sleep Coach that lets people track their sleep patterns nightly in their own bedrooms.

    You sleep wearing a soft headband with sensors that monitor your brain waves and send signals wirelessly to a device that looks like a sleek clock radio. It displays whether you are awake or in light sleep, deep sleep, or REM sleep, in real time, all through the night.

    'If you can measure it, you can manage it,' says Stephan Fabregas, one of two recent Brown University graduates who invented the Zeo because they were looking for a way to wake up feeling less groggy after late nights.

    I knew I wasn't getting enough TIB, but I was stunned to see how little of my time in bed I was actually asleep. The Zeo showed that I woke up numerous times and was awake for long stretches of the night, without having any recollection. （Perception of time is often distorted at night -- many people with insomnia actually sleep more than they think they do.） Even though I was in bed for six or seven hours each night, I was averaging only about four hours of real sleep and very little REM or deep sleep. No wonder I feel so tired!

    The Zeo stores the information on a memory card you can upload to a Web site, which helps track your sleep patterns and sends daily coaching tips for getting better sleep. The $399 device comes with six months of daily email coaching, which can be extended at a cost of $99 for each additional six months. （Currently, it's available only online at www.myzeo.com.）

    To help you keep track of your sleep, the Zeo also gives you a 'ZQ' score every morning, based on the quantity and quality of your sleep the night before. There's no ideal ZQ -- you're comparing your own score from night to night. But the average for people in their 20s is 86; for those in their 40s, it is 74; and for those in their 50s, it is 67, since sleep quality declines with age.

    My ZQs bounced from the 40s to a dismal 15 the first week. Switching to decaf after 3 p.m. and making an effort to get to bed earlier helped me bring my score into the 50s the second week. （'Having caffeine even first thing in the morning can induce changes in brain activity during sleep,' says Kenneth Wright, director of the Sleep and Chronobiology Lab at the University of Colorado at Boulder and one of Zeo's scientific advisers.） I also noticed that the nights when I had the longest stretches of wakefulness were those when my column was due -- probably a sign that I was still thinking about it long after turning in.

    Everybody's sleep and sleep disruptors are different. Todd Johnson, a 40-year-old border-patrol agent in Caribou, Maine, and one of ZEO's early testers, found that reading before he went to bed helped reduce his wake time and bring his ZQ from the 20s into the 60s. 'You can try something that night and see the results in the morning,' he says. Another early tester, Tim Guirl, who teaches at a community college in Seattle, found that he had more restorative sleep if he didn't exercise too close to bedtime and eliminated a large late-night snack.

    Other recommendations from Zeo include reducing noise, light and disruptive influences like pets in the bedroom; having a 'power-down' hour before bedtime with no email, no Internet use, no cellphones and no BlackBerrys; and keeping a consistent sleep schedule. And if you find yourself awake and worrying, Zeo recommends getting out of bed and writing down what you're thinking about in a 'worry journal.'

    The Zeo's brain-wave results have proven similar to those from professional sleep labs -- but only about 140 people have tested it so far. And the Zeo isn't designed to diagnose actual sleep disorders, which plague an estimated 70 million Americans -- you need to see a doctor for that.

    To see if something besides drinking coffee and thinking great thoughts was affecting my sleep, I underwent a sleep study at the Sleep Health Center connected with Brigham and Women's Hospital in Brighton, Mass. A polysomnography, as such tests are called, measures brain waves like the Zeo, but also heart rate, respiratory rate, oxygen saturation, body positions and movements. It took about 45 minutes to have all of the sensors and wires attached -- and then a little longer to get comfortable enough to sleep.

    To my surprise, the study found that I had a fairly severe case of Periodic Limb Movements, episodes of involuntary muscle movements in the night. About 10% of adults have PLMs. Many don't even notice; sleep partners are often bothered more than the sleepers themselves. But PLMs can be very disruptive if they are accompanied by arousals from sleep. I was averaging 42 arousals per hour. According to David White, another Harvard sleep physician who prescribed the study for me, PLMs can be due to an iron deficiency or medication side effects, and they are often related to 'restless-leg syndrome,' which causes an irresistible urge to move the legs, day or night. Medications like Requip can minimize the movements; I'm going to give them a try.

    The study also showed I had some obstructive sleep apnea, in which the airway narrows, especially when the muscles relax in sleep. People with OSA stop breathing momentarily until a lack of oxygen alerts the brain, which wakes them up with a gasp. These mini arousals can occur as often as 70 times an hour, leaving the sufferer exhausted and at risk for heart disease, stroke and atherosclerosis. An estimated 4% of men and 2% of women have OSA. One telltale sign is having a shirt-collar size larger than 17 inches. Another sign is loud snoring, although I certainly don't do that. （'Women never snore -- they all deny it,' says Dr. White.）

    The most effective treatment is a Continuous Positive Airway Pressure machine, which blows air through the nose to keep the airway open. My OSA isn't that bad -- yet. Other remedies include a dental appliance that helps prop the airway open and losing weight, which helps reduce the airway blockage.

    Dr. White is also chief medical officer for Philips Home Healthcare, which makes a watch-like monitor, called an Actiwatch, that tracks whether the wearer is moving or still, roughly corresponding with sleep. The Actiwatch doesn't show sleep phases; it generally diagnoses problems with jet lag and body clocks. I wore one for a week, and although I'm still a night owl, it showed nothing amiss in that area.

    All in all, 'there are plenty of ways you can improve your sleep,' Jason Donahue, another Zeo founder, tells me cheerily. This week, I'm starting in on Zeo's tips on keeping disturbances in the bedroom to a minimum. The dog may have to find a new place to sleep.

    如果問《華爾街日報》的讀者們睡眠是否充足，許多人或許會回答說："哈！"

    美國睡眠基金會（National Sleep Foundation）建議成年人每天的睡眠時間達到7至9個小時。不過根據該基金會的數據，20%的美國人每晚睡眠時間不足6小時，近三分之一的人因擔心財務狀況失眠。該機構負責人德洛？布尼奇（Darrel Drobnich）說，"美國社會認為只有懶蟲──或者是傻瓜才會睡大覺。"

    不過睡眠不足正在嚴重損害著人類的健康。長期的睡眠不足會加大患心血管病、抑郁癥、糖尿病和肥胖的風險，損害認知功能、記憶力和免疫系統，每年還會引發超過10萬起機動車事故。睡眠不足還會改變身體的新陳代謝節奏，導致食量增大、飲食帶來的滿足感下降。

    美國睡眠醫學學會（American Association of Sleep Medicine）最近在西雅圖年會上公布的一些研究顯示，睡眠不足會導致大學生GPA成績下降，而且還與內脂素水平上升有關。內脂素是一種由肚子上的脂肪組織分泌的荷爾蒙，而這些脂肪與抗胰島素有關。

    許多人沒有意識到的是，即使他們躺在床上的時間足夠多（睡眠研究者稱之為在床時間TIB,Time in Bed）,也可能沒有得到高質量的睡眠，不足以恢復精力。出現夢境的快速眼動睡眠期（REM）對于加強記憶力、學習能力、創造力、解決問題和平衡情緒的能力非常關鍵。深層睡眠，亦稱慢波睡眠（slow-wave sleep）對于身體的生長和肌體恢復至關重要。而且在這一階段，人體分泌出身體生長所需的荷爾蒙。快速眼動睡眠和深層睡眠時間都會隨著年齡的增長而減少，而且對于從咖啡因、酒精，到焦慮和一系列睡眠障礙的干擾都非常敏感。

    沒有得到足夠的恢復性睡眠的一個特征是早上起不來，白天睡不醒（這一癥狀稱作EDS）."人們會說，'哦，我沒有睡眠問題。我隨時隨地都能睡著。'──不過這意味著你非常困倦，"哈佛醫學院睡眠醫學教授查爾斯？切斯勒（Charles Czeisler）說。

    其他睡眠不足的癥狀表現包括情緒多變、難以集中注意力、記憶力衰退和長期依賴咖啡因，而這些表現又造成了依賴和干擾的惡性循環。我就是這樣的人。

    要想知道自己的睡眠情況，人們通常需要在專業的睡眠實驗室呆上一晚上，身上接滿各種線路和監視器。不過，我最近在家測試一種名為Zeo Personal Sleep Coach的新型家庭睡眠監測儀。它讓人們可以在自己的臥室里跟蹤自己夜晚的睡眠狀況。

    你需要在睡覺的時候戴上一條柔軟的發帶。發帶上面裝有用來監測腦波的傳感器，它能將信號無線傳遞到一個看上去像電子鐘收音機的裝置上去。該裝置能夠實時顯示你的睡眠狀態：比如你是醒著，處在淺睡、深度睡眠還是快速眼動睡眠狀態。

    斯蒂芬？法布里加斯（Stephan Fabregas）說，"如果可以衡量睡眠，那么你就能夠控制睡眠。"他和另外一名同樣也是新近從布朗大學（Brown University）畢業的學生一道發明了Zeo.他們的初衷是想找到一個解決熬夜之后早上醒來時昏昏沉沉的辦法。

    我心里清楚自己躺在床上的時間不夠多，不過當我知道自己每天真正花在睡眠上的時間只有那么一點點，還是大吃了一驚。Zeo顯示，我夜里醒來過很多很多次，而且在夜晚大段大段的時間里都沒有睡著，而這些我卻完全不記得。（時間感在夜晚通常會變得不準確──許多失眠者的睡眠時間實際上比他們預想得要多。）即便我每晚在床上的時間有6至7個小時，真正的睡眠時間平均下來也只有大約4個小時，而快速眼動睡眠和深層睡眠時間更是少之又少。難怪我會感覺疲勞！

    Zeo會將所有這些信息儲存在一張記憶卡上，然后將信息上傳到一個網站。該網站可以幫助你跟蹤你的睡眠模式，還會每天發送指導建議教你如何改善睡眠。Zeo售價399美元，購買商品附送半年的每日電子郵件指導，額外訂閱電子郵件的價格為每半年99美元（眼下，該服務僅通過www.myzeo.com網站在線提供）

    為了幫助你跟蹤自己的睡眠情況，Zeo還會在每天早上根據前一晚的睡眠時間和睡眠質量為你評出一個"睡商（ZQ）"分數。睡商并沒有優劣之分──你所要做的只是和自己作比較。不過，二十幾歲年輕人的平均ZQ分是86,四十幾歲的平均分是74,五十幾歲67分，這是因為睡眠質量會隨著年齡的增加而下降。

    我的睡商分數在第一個星期從40多分下降到令人沮喪的15分。下午三點以后改喝不含咖啡因的咖啡、盡量早點兒休息讓我在第二周將分數提高到了50多分。（"即便每天早上一醒來就喝有咖啡因的飲品，在晚上睡覺時大腦活動還是會有變化，" 科羅拉多大學波爾得分校（ University of Colorado at Boulder）睡眠和生物鐘實驗室負責人肯尼思？懷特（Kenneth Wright）說，他也是Zeo的科學顧問之一。）我還注意到，我晚上失眠時間最長的時候都在我的專欄文章截稿日──或許這意味著我在交稿很久以后還在想著稿件的事。

    每個人的睡眠狀況和影響睡眠的因素都不一樣。40歲的托德？約翰遜（Todd Johnson）是美國緬因州的邊境巡警，也是Zeo早期的測試者之一。他發現，每晚睡覺前讀書有助于自己的睡眠，他的睡商分數也因此從二十幾分提高到了六十幾分。"你可以晚上嘗試做些什么事情，然后早上看看效果如何，"他說。另一位早期測試者蒂姆？圭爾（Tim Guirl）在西雅圖的一個社區大學教書。他發現，如果自己不在睡覺前鍛煉，并取消晚上那一大份夜宵的話，就會得到更多恢復性的睡眠。

    Zeo的其他建議還包括：減少噪音、燈光和其他因素的干擾，比如臥室中的寵物；在睡覺前有一小時"不插電"的時間，也就是不收發電子郵件、不上網、不打手機、不用黑莓（BlackBerry）;保持一個固定的睡眠時間。如果你發現自己憂心忡忡、睡不著覺，Zeo建議你起床，并在"憂慮日記"里記下自己為什么擔心。

    事實證明，Zeo的腦波結果和專業睡眠實驗室的結論很接近──不過到目前為止只有大約140人接受過Zeo測試。此外，Zeo并不能用來診斷困擾七千萬美國人的真正的睡眠失調──你需要去看醫生。

    為了搞明白除了喝咖啡和思考"偉大思想"之外，還有什么事情影響我的睡眠，我到位于馬薩諸塞州布萊頓（Brighton）的布里格姆婦女醫院（Brigham and Women's Hospital）睡眠健康中心進行了一次睡眠測試。多導睡眠監測能夠像Zeo一樣測量腦波，此外還可以測試心率、呼吸頻率、氧飽和度、身體姿態和動態情況。將所有監控儀和線路連接好花了大約45分鐘的時間──我用了更長的時間才進入夢鄉。

    讓我驚訝的是，測試發現，我有相當嚴重的周期性肢體運動障礙──一種在夜間反復發生的不自覺的肌肉運動。大約10%的成年人患有周期性肢體運動障礙。許多人根本不知道自己有這個毛病；同床者往往比睡眠者更受干擾。不過，如果伴隨有突然的覺醒，那么周期性肢體運動障礙造成的干擾會大得多。我每小時平均的覺醒次數是42次。根據另一位哈佛大學睡眠學家大衛？懷特（David White）的看法，周期性肢體運動障礙有可能是因為體內缺少鐵質或者是藥物治療的副作用所致，這種癥狀還通常和"不寧腿綜合癥"有關。不寧腿綜合癥迫使肢體發生不自主的運動，無論白天還是黑夜。Requip等藥物可以最大化地減少肢體的活動；我會試試這種藥。

    測試還顯示，我有睡眠呼吸暫停的癥狀，這是因為呼吸道受到松弛肌肉的阻塞。患有睡眠呼吸暫停的人呼吸會突然停止，直到缺氧的信號傳遞到大腦，將你喚醒。這些微覺醒每小時可以出現70次之多，導致患者精疲力竭，還有突發心臟病、中風和患動脈硬化的風險。大約有4%的男性和2%的女性患有睡眠呼吸暫停。患病的一個信號是襯衣領口號碼大于17英寸。另一個信號是鼾聲如雷，盡管我肯定不屬于這一情況。（懷特說，"女人們從不打鼾──她們都不承認自己打鼾。"）

    最有效的治療方法是使用持續正壓通氣機（Continuous Positive Airway Pressure）,通過將空氣送入鼻腔來保持呼吸道暢通。我的睡眠呼吸暫停還沒有那么嚴重──起碼到現在為止。其他治療方法包括使用牙科器械和減肥，前者能夠幫助撐開呼吸道，后者能緩解呼吸道的阻塞。

    懷特還是飛利浦家庭醫療保健（Philips Home Healthcare）的首席醫療官。飛利浦生產一款名為Actiwatch、外型類似手表的監控器。它能夠追蹤佩戴者是在動還是保持靜止，大致和他的睡眠相對應。Actiwatch并不能顯示睡眠階段；但能夠用于診斷時差和生物鐘問題。我佩戴了一個星期，盡管我還是個夜貓子，Actiwatch顯示我在這些方面沒有異常。

    總而言之，"改善睡眠的方式有很多，"Zeo另一位創始人詹森？多納赫（Jason Donahue）高興地對我說。從現在開始，我采納了Zeo盡量減少臥室干擾的建議。我的狗或許需要找到個新地方去睡覺了。