• Kimberly

The only blog post you need to read this Thanksgiving

125 studies about the power of gratitude

Here’s a thing about monkeys. They groom each other a lot.

Many animals groom each other; it’s very adaptive for hygiene and managing insects and mites. But monkeys spend way more time grooming each other than they would need to for hygiene alone—they spend nearly 20% of their waking hours on it.

Researchers think all this grooming serves to facilitate, manage, confirm, and repair social relationships. Basically, they groom each other to feel close.

And we know what’s going on in monkey brains when they do that grooming: it's something called the mu-opioid receptor system. While oxytocin and dopamine and other chemicals play a role in developing emotional bonds, it’s the mu-opioid receptor (MOR) system that governs the stable, long-term relationships that make up primate society. The MOR system activates monkeys to reach out socially by grooming or requesting grooming, and helps them feel more socially secure and relaxed during grooming sessions. Primate groups stick together through wind and rain, feast and famine, fights and reconciliations, because their MOR systems foster a feeling of closeness and belonging through the ritual of grooming.

Human primates have an MOR system too.

Our MOR system is also related to social belongingness, helping behavior, and reduction of stress, just like other primates. But we don’t manage our social relationships by picking lice from one another’s heads (at least, not usually). We have a different ritual that, some researchers believe, serves the same purpose as grooming, that activates the MOR system to promote relationships and reduce stress.

In humans, we call it Gratitude.

It is the feeling we get when someone does something kind that they don’t need to do, or when we reflect on the good things in life, or when we look for the hidden benefits and blessings we’ve gotten from our struggles. Feeling gratitude, especially toward human actions, strengthens our social bonds and increases our sense of wellbeing, just as grooming does for other primates. It literally changes our brain in ways that improve our lives and relationships.

In the United States, we traditionally gather once a year ostensibly to give thanks, but often just to hang out and eat too much food. As we approach the yearly gluttony, I thought I would share my gathering of research into gratitude and its effects on the human psyche. Because when humans come together to feast and celebrate as family, friend, and neighbor groups, it’s not just about the food. It is about the MOR system rituals that, for hundreds of thousands of years, have bound us into groups that help and sacrifice for one another.

Researchers have found the markers of this system revealed in human feelings and behavior in hundreds of studies. I have gathered more than 125 pieces of evidence here, for your Thanksgiving-preparation pleasure. You're very welcome.

1. Gratitude makes people happier

Research is overwhelming that gratitude makes people happier. People who are more thankful than others, whether by nature or habit, are happier, more hopeful, and less materialistic than their peers who are less grateful.

But gratitude is also something you can learn. In one study, subjects were randomly divided into two groups. One group would keep a journal every day describing three hassles they had faced that day, the other group would describe three things they were grateful for. At the end of two weeks the gratitude group was significantly happier than the hassles group.

Since the groups were randomly divided, it’s not likely one group just had a better time than the other. But if you’re worried about that possibility, check out other similar studies that found the same correlation between gratitude and happiness in varying groups, including therapy patients and the elderly, here, here, here, here, here, here, here, here, here, here, here, here, here, and here.

Another study had people write a specific, heartfelt letter of gratitude to someone who had helped them. People who wrote these letters were happier than a group that wrote for the same length of time about their deepest feelings. More important, the gratitude writers were still happier three months later. (More here.)

In fact, gratitude interventions like these are shown to have increasing effects over time. It seems to be that when we focus on what we are thankful for, we not only feel better in the moment but also train our brains to notice more things to be thankful for.

Gratitude creates an upward spiral of happiness.

2. Gratitude strengthens relationship bonds

Gratitude has overwhelmingly been shown to improve people’s relationships. Researchers have found that feeling and/or expressing gratitude helps keep relationship bonds strong in romantic and marriage relationships, here, here, here, here, and here. This is true even when the marriage faces severe stressors, like financial insecurity or emotional attachment problems.

Gratitude also helps initiate social relationships, providing a safe foundation to a friendship. And for existing relationships, expressing gratitude improves feelings of closeness and connection and makes us feel more supported. It increases interpersonal trust and makes it easier to forgive. Gratitude is also antithetical to violence and aggression; gratitude interventions have been shown to reduce both.

Moreover, feeling gratitude makes us feel more like doing things to help others. See here, here, here, here, here, here, here, and here. Researchers call this “prosocial” behavior and it covers everything from doing favors to offering praise and appreciation to cooperating on tasks at work.

Thankfulness is also contagious; we often respond with prosocial actions just from seeing someone else feel gratitude. When we are grateful we unconsciously adopt other people’s goals (but not when we are joyful). And one spouse’s gratitude can improve the other spouse’s depression. Gratitude is fundamentally a social emotion; it sends its tendrils out to every aspect of our lives to bind us closer together.

The most amazing part is that when we feel gratitude, we feel closer to others and are more inclined to help them. Then they have a chance to feel gratitude, which makes them feel closer and more connected to us and others in their circle, and inclines them to do nice things for others as well. It is another upward spiral of increasing kindness, and another indication that gratitude is a key facilitator of human social relationships.

3. Gratitude protects against Depression, PTSD, and burnout

It’s not just about feeling better. Gratitude also helps protect from the negative psychological effects of traumatic events. Adolescents who are more grateful are also markedly less likely to ideate about suicide, even when they experience bullying. In fact, gratitude protects against suicide ideation in general.

And research has repeatedly shown that feeling gratitude, whether through a writing intervention or as a general trait, protects people from developing depression even when they are chronically ill. See also here, here, here, here, here, and here. In some cases, gratitude writing exercises can improve depressive symptoms and wellbeing in psychotherapy patients who are already struggling with mental health.

Feelings of thankfulness also protect against PTSD and other trauma symptoms for war veterans and victims of school shootings, terrorism, and natural disasters. There is brain imaging evidence that gratitude reduces hyperactivity in the insula, a brain region involved in post-traumatic stress responses. That would be consistent with PTSD and trauma findings, and also with experimental results that show that gratitude helps improve emotion regulation. It helps stop people’s emotions from “running away with them”, so to speak.

And in activities where people are prone to physical and emotional stress, feelings of thankfulness help protect against burnout. This is especially important in health care professions, where burnout is high but need is great; a little bit of gratitude goes a long way toward keeping health care providers engaged.

4. Gratitude miscellany

Sometimes, studies find effects among American college students that just don’t apply to people in other cultures. But gratitude research has found consistent results among different ages and cultures, here, here, here, and here, in addition to many of the links above. And the effects of gratitude are completely distinct from the effects of personality traits—anyone can choose gratitude, it’s not just for extraverts or the empathetic.

Some aspects of gratitude research aren’t quite so well fleshed-out, but are still quite fascinating. For example, gratitude is implicated in job satisfaction and leadership performance, and has been shown to have a role in academic performance by increasing persistence.

Gratitude seems to improve some aspects of recovery from heart attacks, and to have an effect on a person’s feelings of health, especially in the elderly (and here). It does not seem to affect health directly, but via increased self-care and other indirect effects of increased happiness.

Gratitude doesn't help addicts become sober, but it does help them stay that way. And it helps improve financial decision-making, improve voter turnout, reduce fear, improve sleep, motivate self-improvement (and here), reduce body dissatisfaction in women exposed to unrealistic ideals, and even protects vulnerable teens from engaging in high-risk behavior.


The thing about humans is, we don’t have to be grateful for anything. We can always tell ourselves that whatever kindness was done was owed to us; that whatever good things we enjoy, we deserve more of them; that whatever we may have gained from our struggles wasn’t worth it. We can always turn our focus away from what we do have to others who have more of it.

We’re humans, not capuchins, and we can decide whether to be grateful or not.

But if we decide to choose gratitude, we have access to our own personal relationship grooming rituals that bond us to others and help us become our best selves. It is an amazing resource that we ought to cultivate throughout the year, not just at the holidays.

Gratitude makes us who we are.

(P.S. Check here for instructions on starting your own gratitude journal)

113 views0 comments