WITHOUT meaning to sound ungrateful, it really is the comedown after the festive cheer: the dreaded thank-you notes. Perhaps you agonise over how to make each sound genuine. Maybe you put off the chore for so long you end up not bothering, or simply feel they are an outdated waste of time. Then there is the skill of mustering the convincing faux-thanks for unwanted gifts.

If writing thank-you letters is a task you readily dismiss, you aren’t alone. It turns out we express our gratitude more rarely than you might assume. But, however you feel about those festive notes, it is time to knuckle down. Because saying thanks could be the best gift you can give, to yourself and others.

The benefits of gratitude have long been championed in religious and philosophical thinking. In recent years, the science has been catching up: it shows that people who feel most grateful generally get a psychological boost as a result. They also have greater life satisfaction , fewer visits to the doctor and better sleep . This has led to gratitude becoming part of our cultural zeitgeist, inspiring a proliferation of gratitude journals, in which you record things you are thankful for, and meditation practices in which you focus thoughts on them. It has also led to renewed interest in the neuroscience and psychology of gratitude (see “ The grateful brain ”).

However, the benefits of actually expressing this gratitude have received less attention. Now evidence is stacking up that shows turning our inner gratitude into action can make our lives even better.

For instance, a simple thank you …