Employers now put clauses about internet usage in their contracts because workers waste almost a quarter of their working day checking their social media accounts.
A report has found that workers waste up to two hours a day checking sites such as Facebook and Twitter.
"Employers are putting protocols and procedures in place to stop this and it's becoming more and more common that they're written into contracts of employment," said Mark Fielding, CEO of the Irish Small and Medium Enterprises Association (ISME).
The employment market report was carried out by recruitment firm Cpl Resources, which also found that 50pc of employers allow their workers to have unlimited social media access.
"Some businesses are able to monitor what's happening on a PC and what the traffic is," said Mr Fielding.
However, the problem is that employees are now able to use their own smartphones in the office.
"There are other employers we've heard of, and this is in the minority, where employees are told they can't use their own devices while at their desk," said Mr Fielding.
He said he has received a large number of requests from small and medium businesses to have contracts updated and the internet usage clause put in.
The Cpl report also found that the job market is shifting, with people being more choosy about where they work.
The research found that one in two job-seekers will turn down a job where social media access is restricted.
Job-seekers said that if they were to take a job at one of these firms they would "at least find a way to get around these restrictions".
"Losing up to a quarter of an employee's productivity is a significant burden on business. Employers should take steps to remedy this where necessary," said Peter Cosgrove, the director of Cpl Resources.
Other findings included a bias towards younger job-seekers.
A total of 70pc of employers surveyed said they would hire a "twenty-something" over other age groups for a job that required between three to five years' experience.