By Claire West
Next time you see a colleague with their elbows on the desk and their head in their hands, give them a nudge because the chances are they will be sneaking forty winks.
Researchers found nearly one third of the British workforce have nodded off at their desk at some point in their career.
Those most likely to fall asleep on the job worked in marketing, advertising or PR.
A similar number admitted dropping off during a particularly tedious business meeting.
Nine out of ten said they had made a mistake because they were too tired to concentrate on the job in hand.
Forty seven per cent said that a bad night's sleep meant that they even struggled to get in to work.
The top reason most gave for not being able to sleep was that they felt ill and seventy six per cent reported that a blocked nose was most likely to affect their performance at work as they have difficulty breathing.
The survey of 3,000 UK adults was conducted by Sudafed to reveal how much of an impact being congested has on a person's life..
Dr Adrian Williams, Professor of Sleep Medicine at Kings College London said: "It is normal to breathe preferentially through your nose when asleep and, not surprisingly, more than eighty per cent of Brits report having the most difficulty sleeping with a blocked nose.
"Ninety six per cent of people stated that congestion causes them to lose some degree of sleep, with nearly a third of people reporting 3 hours or more lost in a single night.
''This amounts to more than moderate sleep deprivation which many well regarded clinical studies have convincingly shown results in poorer daytime performance, and in some, excessive sleepiness."
More than a quarter of Brits say they don't like having sex when they have a blocked nose and thirty six per cent stop going to the gym.
Ninety per cent said that their productivity dropped with more than half saying they hate answering the phone and seventy per cent admitting to being conscious of how their speech was affected while being congested.
Nearly a quarter stop going out for a drink until they recover and a fifth stop phoning friends and relatives because they find it difficult to talk.
Nearly a third say they argue more with their partner and two thirds admit that they are grumpy and short tempered when they are congested.
Forty four per cent said they feel that no one wants to be around them when they have a blocked nose and feel that people won't even sit next to them.
Dr Adrian Williams added: "The best advice for people suffering from congestion is to sleep slightly propped up, make sure the room is cool and airy and have some hot water, lemon and honey before bed. An over the counter decongestant may help and always have a bottle of water by the side of your bed."
Nurses were most likely to find it difficult to go to work when they are tired and call center staff were the ones that were least likely to be productive.