Researchers found that workers forced to toil in windowless rooms had a poorer quality of life and more erratic sleep patterns than those with access to daylight.

不仅仅工作压力会使员工们夜里辗转反侧，坐得离窗户太远也能减少掉夜里正常睡眠46分钟。

The findings, published in the Journal of Clinical Sleep Medicine, suggest the working environment may be crucial to setting the body's own internal clock.

Researchers say better designed offices could boost the physical and mental health of workers.

"We suggest that architectural design of office environments should place more emphasis on sufficient daylight exposure for workers in order to promote health and well-being," said Dr Ivy Cheung of the Department of Neurology, Northwestern University, Chicago.

"Office workers with more light exposure at the work place also tended to have better sleep quality, more physical activity and a better quality of life."

A sunny day is equivalent to about 10,000 lux or higher of light. However indoor office lighting typically provides only about 300 to 500 lux.

One in three Britons suffers from poor sleep, with stress, computers and taking work home often blamed for the lack of quality slumber（睡眠）.

However, the cost of all those sleepless nights is more than just bad moods and a lack of focus.

Regular poor sleep raises the risk of serious medical conditions like obesity, heart and diabetes - and can even shorten life expectancy.

Adequate exposure to natural daylight is known to be crucial for governing the body's circadian rhythm - the built-in clock which dictates our sleeping and waking patterns.