Over the past week or two, I’ve been looking for internships as a way to spend my four-month summer vacation. As a rising marketing communications senior, I’ve been searching for more “business-related” positions in order to prepare for my future career.

Throughout this process, there’s been one common trend I haven’t been able to ignore. Whether full or part-time, none of these positions have appeared as following the conventional 9 to 5 work mentality. This unconventional structure has come as a huge surprise to me, considering all the preparation Millennials are given toward this mentality in places such as college.

While I have often heard about the idea of Millennials ending the 9 to 5 work mentality, after having actually experienced this change, I am truly convicted.

With this, I conducted some research on the subject, and ended with tons of information to back it up.

One of the primary reasons the 9 to 5 office worker will become a thing of the past is due to our evolving productivity cycle.

Productivity levels typically peak twice a day. The first “productivity-peak” usually happens first thing in the morning, and the second peak shortly after lunch. The primary reason for this limited amount of productivity, when compared to the 9 to 5 mentality, is due to a huge change in the kind of work that modern day employees typically perform.

An 8 hour work day, five days a week, makes sense for physical labor and manufacturing work. Yet, in the case of the modern information worker nearly all tasks involve creative or strategic thinking. The way someone answers an email or interprets a piece of information can differ drastically depending on his or her energy level.

With this, the main problem with an 8 hour work day becomes mental fatigue. Considering the 9 to 5 mentality requires the appearance of constant productivity, the result is millions of unproductive workers trapped at their desks when they’d rather be doing something else.

Another reason for the decline in 9 to 5 workers, is solely due to the needs and preferences of Millennials. Up until a few years ago, most everyone based their employment offers on 3 factors: salary, benefits, and commute. Yet today, Millennials are increasingly basing their employment on numerous other factors including flexibility, company reputation, and whether or not the job permits them to make a larger impact: Millennials increasingly require some aspect of personal fulfillment from their jobs, and are willing to walk if they do not find it.

With employee turnover rates rapidly rising across the country, and causing companies an average cost between $15,000 and $25,000 to replace each person, research on the Millennial shift away from the 9 to 5 work-mentality becomes extremely important for employers to consider.

Nonetheless, it’s important for employers to realize that with new generations, inevitably come different needs. Thus, changing needs will continuously require them to adapt accordingly.