夜里辗转难眠？你该归咎于你的办公室

Forget milky drinks, hot water bottles or curling up with a good book.

The real secret to a good night's sleep may be where you sit at work.

Not only can the stress of work leave employees tossing and turning, but sitting too far from a window can knock 46 minutes off a normal night’s sleep.

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.

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.

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.

They recruited 49 office employees, just over half of whom spent the day in mostly windowless environments, while the rest enjoyed frequent exposure to daylight through windows.

Each one was quizzed on sleeping patterns, physical activity and general lifestyle.

Some of the volunteers also wore high-tech watches round-the-clock for a fortnight to measure their light exposure, levels of physical activity and sleep/wake times.

The results showed those with the most work-time light exposure snoozed an average of 46 minutes more per night than their light-deprived colleagues.

They also scored better on a sleep quality scale and reported fewer night-time disturbances.

Scientists also found they were more likely to exercise, having got a good night's sleep.

The study backs up earlier research suggesting that nurses are less likely to face burnout from work-related stress and more likely to achieve job satisfaction if they have exposure to at least three hours of daylight a day.

Independent sleep expert Dr Neil Stanley said the body needs exposure to daylight to keeps its sleeping patterns on track.

"Light is essentially the thing that tells our bodies to be awake and dark tells them to go to sleep.

"The problem with office lighting is that it is not made up of 'blue' light, which is the wavelength of light you get from the sun and which controls your body clock.

"So you could have a very well lit office but it does not have the same effect because it's artificial and does not contain blue light."