The science is in: Working 18-hour days, six to seven days a week, will actually make you less productive. However, many of us still convince ourselves that putting in more hours will make us more successful. This belief is especially prevalent in the United States, where over half (55 percent) of people don't take all their vacation time.

Some people may think that foregoing vacation for their career will make them a better employee. However, scientific research has found that the opposite is true. As a human behavior scientist and author of The 2 AM Principle, I have spent over a decade traveling around the world. One of the many things I have learned along the way is that the human body and mind need occasional breaks. Vacations provide rest and a ton of other benefits that have a greater influence on your success and happiness than clocking in overtime at the office. Here's why:

1. Sleep is vital

According to several research studies, the No. 1 impact on our happiness is sleep. This often surprises people. Once your basic needs like food and shelter are fulfilled, more money won't have a huge influence on your happiness. On the other hand, it is nearly impossible to enjoy anything if you are physically exhausted. Lack of sleep negatively affects your cognitive processes, decision making, and alertness.

2. Nature helps us focus

Your environment can play a huge role on your performance. Researchers from the University of Michigan looked at the cognitive benefits of attention restoration theory (ART). Students completed a cognitive test and were then individually sent on a walk through the busy streets of Ann Arbor, Michigan, or a nature-filled arboretum. When they returned, the two groups were tested again, and the students that went to the arboretum scored significantly higher. According to ART, spending a little time out of the office and in nature can actually improve your focus and performance.

3. Novelty sparks creativity

Familiarity and routine can stifle our desire to explore and understand. Researchers Nico Bunzeck and Emrah Düzel examined the brain's SN/VTA, also known as the "major novelty center." They found that the more an individual is exposed to the familiar, the less the SN/VTA responds. However, when exposed to things that are new and novel, it has a heightened reaction that pushes us to explore and understand.

Creativity can be seen as the ability to make connections between disparate ideas, but unless you have explored a wealth of experiences, you will not have anything to draw from. Going on vacation provides a wealth of novelty to spur creativity.

4. It changes your perspective

If you are always around the same people, you'll always think the same way. Sometimes that can be good, but too often, it isn't. Going on a vacation and immersing yourself in new surroundings and cultures can open your mind and forever change the way you view the world. A vacation can allow you to develop a greater global perspective. When you return to the office, the wealth of real-life experiences that you have to offer can make you an even more valuable asset than before you left.

Overworking yourself isn't going to make you more likely to succeed. If anything, it may make you resent your work, lower its quality, and negatively impact your happiness. Take those vacation days, get some rest, and go somewhere exciting.