The Mid-Autumn Festival – sometimes called the Moon Festival or the Day of Reunion – is a 3,000-year-old holiday that’s one of the most important in China and Vietnam. Elaborate lantern displays and “moon cakes” are all part of the celebration, which takes place on the 15th day of the eighth lunar month each year.

Emmons is one of the pioneers of research into the ways that gratitude affects our lives. To assess people’s levels of thankfulness, Emmons and his colleague Michael E. McCullough created a questionnaire that allowed them to compare “grateful people” to those who were less so. They also found ways to cultivate gratitude in test subjects — keeping a “gratitude journal,” counting one’s blessings, writing letters of thanks — then studied the changes that occurred as a result.

The results of his studies and others — both psychological and physiological — are fascinating. Here, five reasons why giving thanks is actually good for you.

• Counting blessings boosts your health. Emmons’ and McCullough’s research showed that grateful people had less depression and stress, lower blood pressure, more energy, and greater optimism.
  
• Slow down the aging clock. In older adults, Emmons and McCullough found, a daily practice of gratitude even slowed down some of the effects of neurodegeneration that often occurs as we age.
  
• Put the brakes on stress. Cortisol is often called the “stress hormone,” and when our bodies produce too much, it can deplete the immune system and raise blood sugar levels. A study conducted at the Institute of HeartMath Research Center in California found that positive emotions like appreciation significantly lowered levels of cortisol.
• Being thankful helps you bond. Research by U.S. psychologists Sara Algoe and Baldwin Way indicates that gratitude also can lead to better relationships. The explanation may be connected to increased production of oxytocin, sometimes called the “bonding hormone” because it fosters calm and security in relationships.
• Gratefulness = good for the heart and waistline? According to research Emmons cites in his book Gratitude Works!, people with high blood pressure who actively express thankfulness “can achieve up to a 10 percent reduction in systolic blood pressure and decrease their dietary fat intake by up to 20 percent.” With Thanksgiving and other food-centered holidays coming up next month, that’s a potential benefit to be grateful for all year long.