A mind filled with fear and bad thoughts is an unquiet mind. When you are worried, it can be hard to direct your attention on even a minor problem.

For some people, this can interfere with work, sleep and other activities. In others, it could lead to a serious mental disorder. People who suffer from anxiety, a nervous disorder, have unreasonable thoughts and fears about the future. Often they are unable to control these thoughts. They are also less able to deal with stress.

Two recent studies found that doing mindful meditation exercises can reduce signs of stress in people suffering from anxiety and make them more productive. The studies also showed that mindful meditation can lower a person’s stress levels.

Meditation is a simple, low-cost way to help calm an unquiet brain. We can define mindful meditation as thinking quietly about what is going on in the present. You don't think about the past or the future. You think only about your own breathing and what you sense around you.

Should you start thinking about a future task or a past mistake, you simply tell your mind to stop and return to the here and now. Another part of mindful meditation is to let yourself experience any thoughts and feelings without judgment.

Around the world, the number of people reporting stress and anxiety is increasing.

The World Health Organization says that between 1990 and 2013, the number of people suffering from depression and/or anxiety rose by nearly 50%. The WHO’s website says this increased the number from 416 million to 615 million people.

This is not just a health issue, but also an economic one. WHO experts estimate that depression and anxiety disorders cost the world economy US$1 trillion each year. Stressed and anxious workers who can't stay focused are not productive.

In one recent study, Canadian researchers wanted to see how well anxious, stressed people completed an activity.

The researchers found that meditating for 10 minutes a day may help keep people's minds from becoming unfocused. So, mindful meditation may help people stay on task.

Mengran Xu is a clinical psychologist at the University of Waterloo in Ontario. He and his colleagues studied with people who showed signs of anxiety.

“We know that anxious people in general, if you ask them to stay on task, it is hard for them. They tend to wander. They tend to worry. But those people who practiced mindfulness didn’t. They were able to stay on task."

In this study, 82 people suffering from anxiety were asked to perform a computer task that required high levels of focus. Then researchers interrupted them as they performed the work. The researchers studied their ability to stay focused.

Then the 82 people were divided into two groups. One group listened to an audio book. The other group did mindful meditation for about 10 minutes.

Finally, researchers asked all the subjects to go back to their computers.

Xu says that those who meditated performed much better on the task.

"The anxious people who listened to the audio books, they performed much worse over time, while the anxious people who practiced mindfulness meditation, they were able to in a way improve and maintain their performance on the task."

The researchers published their findings in the journal Consciousness and Cognition.

The other study is from the Georgetown University Medical Center in Washington, DC. For this study, researchers looked at 89 patients who have an anxiety disorder.

The researchers divided the patients into two groups. One group took a mindfulness meditation training program for eight weeks. The other group -- the control group ? took a class on Stress Management Education for eight weeks.

People from both groups were asked to do something stressful. They had to give a short speech in front of a crowd -- not once but twice, both before and after their training.

During each speech, researchers measured levels of hormones and proteins that the body releases when a person is feeling stressed.

The control group, researchers said, showed small increases in stress on the second speech compared to the first. This suggests their stress and anxiety levels increased when they had to give the speech again.

However, when making the second speech, those who used mindful meditation produced fewer stress hormones and proteins. This suggests that meditation worked to reduce stress.

Elizabeth A. Hoge is a doctor and works in the medical center's Department of Psychiatry. She says people who used mindful meditation had "sharply reduced stress-hormone" levels and other biological responses to a stressful situation. And those who took the stress management training had poor responses.

Hoge and her colleagues reported their findings in the journal Psychiatry Research.