The Harvard Study of Adult Development began tracking the lives of 268 Harvard sophomores in 1938.

It is considered the longest running study on adult life, health, and happiness.

Here are 3 powerful findings everyone should know:
Finding: Relationship satisfaction impacts health.

The researchers looked back at the lives of the 80-year-old participants to determine what factors were predictive of healthy aging.

What did they find?

Relationship satisfaction at age 50 was predictive of health at age 80.
Study director Robert Waldinger:

"It wasn’t their cholesterol levels that predicted how they were going to grow old. It was how satisfied they were in their relationships. The people who were the most satisfied in their relationships at age 50 were the healthiest at age 80."
Finding: Loneliness kills.

Humans are social creatures. We thrive through connection to those around us.

Study participants who felt isolated were observably less happy and experienced notably earlier declines in health than those who felt connected.
The study observed the negative impacts of alcohol and smoking on the long-term health of the participants, but found that loneliness was just as negatively impactful.

Study director Robert Waldinger:

"Loneliness kills. It’s as powerful as smoking or alcoholism."
This finding on loneliness is interesting in the context of the chart I shared last week on the amount of time we spend alone over the course of our lives.

While we need to learn to embrace solitude, the quality and depth of our social connections is critical to our well-being.
Finding: Quality over quantity.

The researchers found that the quality of relationships was more impactful on health and happiness than the quantity of relationships.

A few deep bonds are worth far more than hundreds of weak or unhealthy ones.
Those are 3 powerful findings from the study that everyone should know.

For more on the study, check out this wonderful 2016 Ted Talk from study director Robert Waldinger.

Follow me @SahilBloom for more writing on growth, health, and happiness.
I'm writing a deeper dive on the study in an upcoming newsletter. Join 130,000+ others who will receive it!
The research was also covered in a recent episode of @hubermanlab podcast.

Worth your time!
One fact I find interesting:

The findings feel “obvious” and yet so many people fail to live in a manner that takes them into account.

We continue to chase status and fame despite an awareness that relationships are what truly matter in the end.

Humans are funny like that.
My best advice on relationships:

When you think something nice about someone, let them know.

It's a shame we often wait until a person's funeral to say all of the nice things we thought about them.

The next time you have a positive thought about someone—tell them right then.
One more suggestion:

Sunday evening walks with your loved ones.

Builds deep connection and releases a whole lot of happiness chemicals.

Smiling is mandatory!

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Extremely important thread, whose lessons you will probably ignore 😊