Around the world, the traditional concept of the 9 to 5 office job is changing. Technology has opened up options for remote working and many companies, particularly in the technology sector, are adopting flexible working hours giving employees autonomy when they start and end their work days.

While working practices may be changing, however, perceptions are not keeping pace.

A series of studies with two researchers from the University of Washington found that employees who take advantage of flexible work time to start work later may be unwittingly risking their career prospects because of the way they are perceived by supervisors.

Flexible working hours are commonly viewed as a win-win for both employees and companies. Recruiters often promote such schemes as a perk because they help staff organise their workdays around family or other commitments for example, or avoid commutes during peak hours.

Google, for instance, allows many employees to set their own work hours, while Microsoft allows their staff to choose when to start their day as long as it is between 9am and 11am.

Companies also benefit as studies have shown flexible work practices result in higher productivity, job satisfaction and lower employee turnover.

But despite such benefits, is there a particular group that pays a price?

Three separate studies found that supervisors in firms with flexible hours have a tendency to look negatively on employees who start work later in the day, deeming them to be less conscientious than those who start work early.

As a result, those staff tend to be rated as lower performers.

Employees who arrived earlier were evaluated to have superior job performance than those who started work later.

This was the case even though both sets of employees worked the same number of hours and achieved the same levels of productivity. The studies took into account demographic information such as age, race and gender to ensure that individual differences did not affect the findings.

This bias was particularly evident for employees whose supervisors were early starters. If their supervisor were a late worker, the perception was mitigated.

So while flexible hours may be commonly seen as a perk for staff, the findings show that on their own, they may actually undermine an employee’s standing during staff review procedures - overshadowing their actual performance within the company.

This bias towards stereotyping later starters means employees risk being inadvertently punished for taking advantage of flexible work time programmes. With an accumulation of poor performance ratings, it may even hold them back in their career advancement.

As staff become aware of this, companies may be unwittingly pressurising their employees to start work early, thus defeating the many benefits associated with a flexible work time practice.

Further, some talented staff may be night owls who have a preference for later starts. Having them pressured to arrive at work early because of this bias may render them counter-productive.

What then can companies do?

Managers must be made aware of their tendencies to stereotype employees who use flexible work time, and adjust for these accordingly.

One way is for supervisors to establish more objective standards for use in performance reviews to minimise their early bird prejudice from colouring their assessment.

Another path may be to have employees raise issues regarding productivity with their supervisors and make it clear that start time is immaterial.

Overall, firms should be aware that simply introducing flexible hours on their own can have ramifications that should also be addressed. Indeed, without changes to their review procedures and other practices, they may ultimately be counterproductive.