Don’t be surprised if you wake up next month feeling particularly happy. Thanksgiving is all about gratitude, and studies have shown that expressing gratitude can increase feelings of happiness for up to one month.

Martin Seligman, a pioneer in the field of positive psychology, has publishedstudies detailing several happiness interventions, including the “gratitude visit.” During the graditude visit, subjects write and then deliver a letter of gratitude to a person in their life who hadn’t been properly thanked for their kindness.

Turns out saying thank you has lasting effects. The subjects in the study felt positive effects for one month after the intervention.

This could be you! This Thanksgiving, make a point of visiting, calling, or writing to someone who has done something nice for you in the past. Let them know how much it impacted you, and see if it makes you feel better. Science says it will.

If you’re like me, you’ll tear up a bit while watching this Soul Pancake video that re-creates the Seligman study with a Doogie Howser-esque fellow in a lab coat and some game volunteers.