People who do not get enough sleep are more than twice as likely to die of heart disease, according to a large British study released Monday.

Although the reasons are unclear, researchers said lack of sleep appeared to be linked to increased blood pressure, which is known to raise the risk of heart attacks and stroke.

A 17-year analysis of 10,000 government workers showed those who cut their sleep from seven hours a night to five or less faced a 1.7-fold increased risk of death from all causes and more than double the risk of cardiovascular death.

The findings highlight a danger in busy modern lifestyles, Francesco Cappuccio, professor of cardiovascular medicine at the University of Warwick's medical school, told the annual conference of the British Sleep Society in Cambridge.

"A third of the population of the UK and over 40 percent in the US regularly sleep less than five hours a night, so it is not a trivial problem," he told reporters.

Previous research has highlighted the potential health risks of shift work and disrupted sleep. But the study by Cappuccio and colleagues, which was supported by British government and US funding, is the first to link duration of sleep and mortality rates.

The study looked at sleep patterns of participants aged 35-55 at two points in their lives - 1985-88 and 1992-93 - and then tracked their mortality rates until 2004.

The results were adjusted to take account of other possible risk factors such as initial age, sex, smoking and alcohol consumption, body mass index, blood pressure and cholesterol.

Cappuccio said it was possible that longer sleeping could be related to other health problems such as depression or cancer-related fatigue.

"In terms of prevention, our findings indicate that consistently sleeping around seven hours per night is optimal for health," he said.

目前其中的原因尚不清楚，但研究人员称，睡眠不足会导致血压升高，从而增大患心脏病和中风的风险。

一项针对1万名政府职员、长达17年的跟踪调查表明，每晚睡眠时间从七个小时减少到五个小时或更少的人因各种原因而死亡的几率是睡眠正常者的1.7倍，而且死于心血管疾病的风险也增加了1倍多。

沃里克大学医学院的心血管药物学教授弗朗西斯哥?卡普西奥在英国睡眠学会在剑桥召开的一年一度的研讨会上说，这一研究成果揭示了忙碌的现代生活中潜在的危险。

他在接受记者采访时说：“三分之一的英国人以及超过40%的美国人每晚的睡眠时间常常达不到五个小时，所以这个问题不可小视。”

此前有调查发现轮班及睡眠中断会对健康产生潜在威胁。但卡普西奥及其同事的这项调查则首次揭示了睡眠时间长短与死亡率之间的关系。该调查由英国政府和美国基金提供资助。

该调查对年龄在35岁至55岁之间的人在1985年至1988年以及1992年至1993年两个阶段的睡眠模式进行了探究，并对这一人群截至2004年的死亡率进行了追踪。

调查还考虑到了调查对象的初始年龄、性别、是否吸烟喝酒、体重指数、血压及胆固醇指标等其它可能的风险因素。

卡普西奥说，睡眠时间过长也可能导致如抑郁症及癌因性疲乏等其它健康问题。

他说：“就预防而言，我们的研究结果表明，每晚睡眠时间持续保持在七小时左右最益于身体健康。”