Individuals who get less than seven hours of sleep per night appear about three times as likely to develop respiratory illness following exposure to a cold virus as those who sleep eight hours or more, according to a report in the January 12 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.

    Studies have demonstrated that sleep deprivation impairs some immune function, according to background information in the article. Research indicates that those who sleep approximately seven to eight hours per night have the lowest rates of heart disease illness and death. However, there has previously been little direct evidence that poor sleep increases susceptibility to the common cold.

    Sheldon Cohen, Ph.D., of Carnegie Mellon University, Pittsburgh, and colleagues studied 153 healthy men and women (average age 37) between 2000 and 2004. Participants were interviewed daily over a two-week period, reporting how many hours they slept per night, what percentage of their time in bed was spent asleep (sleep efficiency) and whether they felt rested. They were then quarantined and administered nasal drops containing the common-cold-causing rhinovirus. For five days afterward, the study participants reported any signs and symptoms of illness and had mucus samples collected from their nasal passages for virus cultures; about 28 days later, they submitted a blood sample that was tested for antibody responses to the virus.

    The less an individual slept, the more likely he or she was to develop a cold. Lower sleep efficiency was also associated with developing a cold—participants who spent less than 92 percent of their time in bed asleep were five and a half times more likely to become ill than those whose efficiency was 98 percent or more. Feeling rested was not associated with colds.

    "What mechanisms might link sleep to cold susceptibility? When the components of clinical illness (infection and signs or symptoms) were examined separately, sleep efficiency but not sleep duration was associated with signs and symptoms of illness. However, neither was associated with infection," the authors write. "A possible explanation for this finding is that sleep disturbance influences the regulation of pro-inflammatory cytokines, histamines and other symptom mediators that are released in response to infection."

    The results suggest that seven to eight hours of sleep per night is a reasonable target, they conclude.

    Source: JAMA and Archives Journals

    據1月12日《內科醫學檔案》刊登的一篇文章說，每晚睡眠不足7小時的人和每晚睡眠在八小時及以上的人相比，在遭遇感冒病毒后患上呼吸道疾病的可能性要大三倍。該雜志是

    JAMA檔案雜志集團旗下的一份刊物。

    根據這篇文章里的一些背景資料顯示，研究表明缺乏睡眠會破壞某些免疫系統的功能。研究結果還顯示，那些每晚睡眠在7到8小時的人患心臟病和死亡的幾率最低。然而，沒有直接證據表明睡眠質量不高會增加患普通感冒的幾率。

    Sheldon Cohen是位于匹茲堡市的卡內基·麥倫大學的博士，他和他的同事們在2000年到20004年之間研究了平均年齡為37歲的153名身體健康的人群。參加試驗者接受了為期兩周的觀察，他們向研究人員報告每晚的睡眠時間，他們在床上有多長時間是用來睡覺的（也就是睡眠效率）以及他們睡眠質量怎么樣。他們隨后被隔離，在指導下服用含有感冒病毒的鼻病毒。隨后的5天里，參加試驗者隨時報告他們出現病癥的跡象，從他們的鼻腔內提取的粘液被用來進行病毒培養。28天后，他們提交一份血樣，來檢驗他們的身體對病毒的抵抗力。

    睡眠越少，越容易患感冒。睡眠效率低，也易患感冒。那些睡眠效率低于92%的人和那些效率在98%以上的人相比，生病的幾率要高1.5倍。睡眠質量跟感冒沒有關系。

     “什么機理導致了睡眠和患感冒的幾率？對臨床疾病的組成（傳染性和癥狀）分別進行研究的時候，睡眠質量而不是睡眠時間和感冒的癥狀有關。然而二者都和傳染性沒關聯。”作者寫到，“對這項發現的一個可能解釋就是睡眠會影響導致發炎的細胞因子，組胺及其他癥狀催化劑，正是這些物質會在傳染時得到釋放。

    他們最后得出的結論是，研究結果表明每晚保證7到8小時的睡眠是一個合理的目標。