People have more control over their health than they may realize. A study of heart patients offers an enlightening look at how a person's outlook on the world can make a difference in their health, even after a serious illness. And it starts with being grateful.

Researchers at the University of California, San Diego found that simply noticing and appreciating the good things in life — experiencing gratitude — went hand in hand with better sleep, better mood, less inflammation and better overall health.

It wasn't so much a person's spirituality that was making them physically healthier, it was how grateful they felt.

The researchers followed 186 people who had been living with heart failure for at least three months. The patients' hearts had been damaged by a heart attack, but they showed no symptoms — such as shortness of breath or fatigue — from the damage. As heart patients, they were, of course, at high risk of developing these and other symptoms of poor heart health in the future.

Participants in the study were given a battery of tests that measured their gratitude, spiritual well-being, depressive symptoms, sleep quality, fatigue, self-efficacy and inflammatory markers in order to look at the relationship between spirituality and gratitude on several health indicators including inflammation.

Other studies have shown that people who consider themselves more spiritual tend to have a greater sense of well-being, which includes better physical health.

It wasn't so much a person's spirituality that made them physically healthier, it was how grateful they felt. Participants' gratitude scores appeared to be behind the health benefits of spiritual well-being on sleep and mood and to partially account for benefits of spiritual well-being on fatigue and patients' belief in their self-efficacy — their ability to maintain a healthy heart.

To further test their results, the researchers asked some of the patients to keep a gratitude journal and to write down daily, for eight weeks, the three things they were most thankful for.

People who kept gratitude journals for those eight weeks showed a drop in several important inflammatory biomarkers, as well as improved heart rate variability while they wrote. Improved heart rate variability is considered a measure of reduced cardiac risk, while inflammation often worsens heart failure.

Whether it's chocolate, a sunset, or simply a day without problems, even the most confirmed pessimist can find something to be grateful for. Realizing this or even writing it down might just open up a hidden road to better health.

The study appears in Spirituality in Clinical Practice.