Researchers followed 68,183 middle-aged women for 16 years and found that those who slept 5 hours or less per night were one third more likely to gain weight than those who slept for 7 hours.

Moreover, researchers found that the weight gain was substantial with some women even gaining 33 pounds or more.

The associations between sleep duration and weight gain persisted even after controlling for factors such as physical activity and calorie consumption in both groups.

The findings, presented earlier this year at a medical conference and published in the American Journal of Epidemiology, furthers the evidence that sleep habits affect a person's weight.

The exact reasons for association between sleep duration and weight gain aren't clear but some research suggests that sleep deprivation alters hormones involved in appetite control and metabolism.

Also it's possible that people who sleep fewer hours either eat more or, because of fatigue, and exercise less often.

The research was led by Dr. Sanjay R. Patel of Case Western Reserve University in Cleveland.

一项由68000多名美国中年女性参加的研究表明，长期睡眠不足的女性容易发胖。

研究人员对68183名中年女性进行了长达16年的“跟踪”调查，结果发现，每晚睡眠时间为5小时或不足5小时的女性发胖的几率比每天睡7小时的女性高三分之一。

此外，研究人员发现，有些女性的体重有较大幅度的增长，16年内增加了33磅甚至更多。

即便是在控制运动量和热量摄入等因素的情况下，睡眠不足仍是导致发胖的主要原因。

这项研究结果是在今年年初的一个医学研讨会上提出来的，并在美国《流行病学》杂志上发表。研究结果进一步说明，睡眠习惯会影响体重。

虽然其中的具体原因目前还不清楚，但已有研究表明，睡眠不足会改变体内影响食欲和新陈代谢的激素水平。

也可能是因为睡眠时间不足的人吃得较多，或者因疲倦而很少锻炼身体。

这项研究的负责人是克利夫兰凯斯西储大学的桑贾伊·R·帕特尔博士。