“I’ll be there for you” is the catchy cry of the “Friends” them song, and the show lives up to this promise. It’s on your TV again and again — and you love it every time.

Turns out there’s a reason you can’t get enough of those reruns, even if you’ve seen them a million times (and no, it’s not Chandler’s quick wit). It’s your psyche. Old reruns are attractive to your brain because they’re the perfect nostalgia trigger. It’s the same reason you re-read the Harry Potter series every so often, listen to Adele’s “Hello” a thousand times or watch “Love Actually” every December 24th.

“There are a great deal of things that we do not at all feel compelled to re-watch or re-read, particularly in a world in which we have access to virtually limitless entertainment and cultural material. The things that we do feel compelled to re-watch or re-read are those that provide us with either comfort or perspective,” psychologist Neel Burton, author of Heaven and Hell: The Psychology of the Emotions, told The Huffington Post.

The things that we do feel compelled to re-watch or re-read are those that provide us with either comfort or perspective.
Psychologist Neel Burton

Here’s how it works: Nostalgia permeates your inner life by being a source of consolation you can tap into anytime you feel lonely or wistful for a period of time that’s already passed. It feels good to reminisce, and even better to escape the current reality. The best part? The effort to do so is moderately low and the reward (as recognized by the brain) is high, Burton says.

“Our everyday is humdrum, often even absurd,” Burton explained. “Nostalgia can lend us much-needed context, perspective and direction, reminding and reassuring us that our life is not as banal as it may seem. It also tells us that there have been — and will once again be — meaningful moments and experiences.”

Researchers are finding that the act of repetition also plays a role. Human beings love predictability. As Derek Thompson writes in The Atlantic, re-watching or re-listening to something makes you feel good because it’s incredibly easy to process:

The scientific term for this is “mere exposure effect,” meaning that we like something more merely because we’ve been previously exposed to it. So there is evidence not only that we replay songs that we like, but also that — up to a certain point! — we like songs the more often that we play them.

Add the power of repetition to nostalgia and you have a combination that’s irresistible to your brain.

That said, what makes something worth reminiscing varies in different cultures. “Our form of nostalgia is perhaps not a timeless and universal human emotion like, say, fear or anger,” Burton explained.

The concept of “nostalgia” is a more abstract idealization of time periods or people in other parts of the world, not something that’s necessarily tied to a specific “trigger.” The ancient Romans, for example, called the phenomenon “memoria praeteritorum bonorum” which psychologists now coin as “rosy retrospection,” Burton said. It means that the past is always remembered in an idealized way.

And it makes sense that there are different cultural definitions of nostalgia — even now. What some consider a comforting staple of their formative or favored years in America (i.e., “Friends”) isn’t going to be the same for someone in, say, Italy, who may have grown up with a different show or without a lot of TV altogether. The outcome may be the same, but the trigger or the process to get us to that wistful place may be entirely different.

Ultimately, Burton says there’s nothing wrong with your affinity for reruns, because there’s nothing inherently wrong with reminiscence as long as you’re not idealizing or completely living in the past. In fact, there are even some scientific benefits: Research shows nostalgia can make people feel more optimistic about the future and can counteract loneliness and anxiety.

“Each time they watch an episode, it’s like meeting up with their friends, catching up with the gossip and having new adventures,” he said. “But, of course, there are only so many episodes, and once they run out, well, what else to do but to re-watch them?”

And re-watch them, you will. We’re just going to go ahead give your life the episode title “The One With ‘Friends’ On Repeat.”

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