UK office workers are only productive for three days in a working week - and just two and a half in hot weather, according to new research.
A poor night's sleep is the biggest cause of an unproductive day, followed by being too hot in the office and being surrounded by distracting colleagues.
IT problems also lead to getting less work done, along with feeling too hungry and the after-effects of having had one too many drinks the night before.
Respondents said they find themselves overtired at work around two days a week, while four in five admit they clock-watch - typically for 55 minutes over the course of a week.
HSS Hire, the leading national supplier of tools and equipment, commissioned the research of 2,000 office workers and also found seven in 10 have had bust-ups over how or cold the office should be.
A spokesman for HSS Hire said: "The results show the wide range of factors affecting our ability to perform at work day in day out.
"The findings also highlight to some degree how our personal well-being - not being too hot, getting enough sleep and so on - really makes a difference to how productive we are.
"It's important to take care of ourselves, but given the recent hot weather, perhaps bosses will have noticed a drop in productivity and will be wondering if there is anything they can do to solve that problem."
On a typical day, 15 minutes are spent gossiping to colleagues, 14 minutes are spent looking at no-work related content on the web and eight minutes are spent making teas and coffees for co-workers.
Friday is the least productive day of the week for Brits and Tuesday is the most productive day.
On average those polled said they are most productive at 10.23am during a typical day and least productive at 2.02pm.
Half of those surveyed suspect that a colleague has sneakily tried to adjust the temperature of the air conditioning without telling anyone.
When the office temperature creeps up, two in five reckon their colleagues are less hard working.
While forty per cent think their co-workers become bad tempered - and one in 10 are more flirtatious.
Half of people polled said their co-workers dress inappropriately whenever the sun comes out - with a quarter coming to work in vests, one in four opting for flip-flops and 17 per cent wearing crocs.
When asked how many hours in total they are productive for during a working week, on average those polled said 22 hours and five minutes - around four hours and 25 minutes a day.
In comparison, when the weather is hot those surveyed said they are typically productive for 19 hours and seven minutes during the working week - three hours and 49 minutes a day.
Despite this, around half of office workers have had requests to have the air conditioning turned on rejected by their boss.
In fact, a fifth have had a boss who has refused to have air conditioning installed despite six in 10 employees claiming it's perfectly acceptable to get less work done when it's stifling.
And four in five office workers admit they get more stressed when it's hot in the office.
While one in five of those polled have no air conditioning at all in their workplace.
On average, respondents said 27 degrees Celsius is the point at which it is too hot to work.
And over three quarters of people polled think we should have shorter working days when the weather is stifling.
A spokesman for HSS Hire said: "We all work hard but certain factors can make our ability to be productive that little bit harder.
"Indeed, the results suggest that workers in cool air-conditioned offices are actually more productive, less stressed and generally happier to be at work."
Top 10 factors that lead to an unproductive day at work:
1. Poor night's sleep
2. Being too hot in the office
3. People talking to you too much (distracting colleagues)
4. IT problems
5. Noisy office
7. Distracted by personal issues in general
8. Feeling too hungry
9. Being too cold in the office
10. Drinking too much the night before
IMAGE DOWNLOAD: Hot employee