Employers are seeing more staff turning up to work while ill, according to a report from the Chartered Institute of Personnel and Development (CIPD).
It surveyed more than 1,000 organisations this year and found that 86% had observed staff attending work while ill, or "presenteeism".
The rise compares with a survey in 2010 when just 26% of employers observed the behaviour.
The CIPD also found high numbers of staff willing to work while on holiday.
The scale of the problem is "shocking" according to Rachel Suff, Senior Employment Relations Adviser at the CIPD who said "people feel under even more pressure to work".
She said employers need to do more to tackle the issue.
"Too few organisations are discouraging unhealthy workplace practices and tackling stress, which is strongly linked to health conditions such as anxiety and depression," Ms Suff said.
Last year, the TUC described UK workers as "mucus troopers" after the Office for National Statistics said that sickness absence totalled 137 million working days in 2016, the equivalent of 4.3 days per worker and the lowest on record.
When records began in 1993, the equivalent of 7.2 days were lost.
There is no official definition for worker sickness. Employees are able to self-certify sickness for up to seven days. For longer periods, and statutory sick pay claims, a doctors note is needed. Some workplaces have their own specific rules.
'Grin and bear it'
Emma Lowe has ulcerative colitis and says that, in a previous jobs, it was tough to make managers aware of the issues.
"I'd been having at least one day off a month due to my UC and I was told that I should 'grin and bear' the pain," she says.
"Unfortunately [my manager] didn't understand that on those days I was off sick, I couldn't even walk, let alone climb the stairs at work and be sat in an air-conditioned cyclone.
"My UC put me in hospital in 2010 and I was out sick for nearly two months. My manager at the time did not understand what UC was and had to Google it. Then he had to explain that I was genuinely sick to higher up."
Official guidance, published earlier this year, suggested that employers should give staff places to rest at work to help boost productivity.
Public Health England said that downtime at work can help employees switch off and get better quality sleep at night.
Experts suggest that millions of pounds are lost owing to absenteeism, and presenteeism - when employees are at work but not operating at optimum levels.
Some firms already encourage employees to have downtime at work. London-based money transfer service firm TransferWise has a hammock and sauna on its premises, for example.
And accountancy company PwC, as part of a training programme on resilience, tries to help its staff improve the quality of their sleep.
The report by the CIPD was written in partnership with Simplyhealth.