Burning the candle at both ends is almost a rite of passage as an executive, business owner, or entrepreneur -- at some point applies to any profession, really. Where a balance can certainly be sought, there just isn't enough time in the day. For those over 40, new research is now supporting that merely working over 25 hours per week could be hazardous to your health.

What the research says.

Researchers for the Melbourne Institute of Applied Economic and Social Research in Australia conducted a study on more than 6,000 workers aged over 40. They were specifically tested on reading, pattern, and memory to gauge how the number of hours per week would effect cognitive ability. Notable findings include the following:

Where previous research supported that working overtime caused cognitive impairment, that same impairment can occur in people over 40 solely working a regular week

solely working a regular week Although a person's ability to process information can start declining at an earlier age, age 40 is when people's performance on memory tests and other exercises designed to test mental agility can start to drop.

Working 40 hours a week at age 40 may be the norm now as the average retirement age has increased -- but the reality is our minds may not be designed for the stress and repetition of these kinds of hours at this age

Those that would be considered "expert performers" worked between 21-35 hours per week. However, they only worked between 3-5 hours and did not exceed 5 hours on any given day.

For men, optimal working hours was found between 25-30 hours per week, which resulted in a "positive impact on cognition". For women, 22-27 hours per week was optimal. Beyond those hours would result in a "negative impact on cognitive functioning"

"Stress affects cognitive functioning primarily through hormones"

Both physical and psychological stress can potentially impair cognitive functioning as a result of excessive work hours

So, what am I supposed to do? Just stop working?

It's hard not to scoff at these numbers because drastically altering your work schedule is simply not feasible, or you may reject the notion that 25 hours is optimal. However, what you can do is take appropriate steps to ensure you're maximizing and optimizing your work week -- like by getting ample sleep. How ample? For people over 26, more than seven hours a night is recommended. Alternatively, try to stay physically and mentally active as much as possible. Have a schedule and stick to it.