How many times have you wanted to take a vacation but thought, I just have too much to do?

How many times have you complained how exhausted you are but without doing anything about it?

How many times have you been frustrated by the long hours you are working, but without giving yourself a rest?

According to a recent survey, the average U.S. employee takes only half of their allotted vacation time. Unsurprisingly, they're suffering from being overworked, overwhelmed and overwrought.

Even among those who actually do go on vacation, three in five admitted to doing some work. A quarter were contacted by a coworker while they were on vacation, and 20 percent were contacted by their supervisor about a work-related issue.

It's time we say "enough is enough" and learn to put our needs first. Taking time off is good for your mental and physical health, and you can come back more productive and effective. It's a win-win.

Here are four science-based reasons you should book your next vacation today:

1. Stress reduction. A study released last year by the American Psychological Association concluded that vacations work to reduce stress by removing people from the activities and environments that they associate with stress and anxiety. Similarly, a Canadian study of nearly 900 lawyers found that taking vacations helps alleviate job stress. The effects last beyond the duration of the vacation, too: A small study from the University of Vienna found that after taking time off from work, vacationers had fewer stress-related physical complaints such as headaches, backaches, and heart irregularities, and they still felt better five weeks later.
2. Heart disease prevention. A host of studies have highlighted the cardiovascular health benefits of taking a vacation. In one, men at risk for heart disease who skipped vacations for five consecutive years were 30 percent more likely to suffer heart attacks than those who took at least a week off each year. Even missing one year's vacation was associated with a higher risk of heart disease. Studies find similar results with women: Women who took a vacation once every six years or less were almost eight times more likely to develop heart disease, have a heart attack, or die of a coronary-related cause than those who took at least two vacations a year. These statistics are not to scare you but to persuade you that time off is important to your health in the long run.

3. Improved productivity. In our perpetual rush to be productive, we often undermine our very ability to consistently perform at peak levels. Getting more done in less time allows us to get ahead and be more productive, but it takes consistent focus to be truly productive. Professional services firm Ernst & Young conducted an internal study of its employees and found that for each additional 10 hours of vacation time employees took, their year-end performance ratings improved 8 percent. What's more, frequent vacationers were significantly less likely to leave the firm. Another study by the Boston Consulting Group found that high-level professionals who were required to take time off were significantly more productive overall than those who spent more time working. When you're more productive, you're happier, and when you're happier, you excel at what you do.
4. Better sleep. Restless nights and disrupted sleep are common complaints--often stemming from the fact that we simply have too much on our minds. When we can't stop the chatter it affects our sleep, and a lack of sleep leads to less focus, less alertness, impaired memory, an increased likelihood of accidents and a decreased quality of life. Researchers say, that vacations can help interrupt the habits that disrupt sleep, like working late into the night or watching a backlit screen before bed. If you have stress from work and you find your sleep is disrupted because of anxiety or tension, take time off and learn to reset your sleep pattern.

As summer approaches, if you've been putting off your vacation, think again. Take some time off so you can sleep better and be more productive, more relaxed, and healthier.