Dopamine fasting — loosely defined as the practice of adopting, for various lengths of time, an extremely ascetic lifestyle in order to reset your brain chemistry — is the sort of thing that feels engineered to go viral. And it has, most recently in October, thanks to a single tweet.

“In an instance of the Bay Area being very Bay Area: today was my first day in SF since moving here, and I ran into someone from my YC batch who told me he was on a ‘dopamine fast’ and thus had to cut our convo short (lest he acquire too much dopamine).”

The original tweet, from Janey Muñoz, was quickly followed by one from the Y Combinator colleague in question: “Essentially refrain from all stimulating activity (food, social media, porn, exercise, music, etc) for 1 wake cycle. Instead, meditate, journal, reflect, think, and shower,” James Sinka wrote on Twitter.

In an instance of the Bay Area being very Bay Area: today was my first day in SF since moving here, and I ran into someone from my YC batch who told me he was on a “dopamine fast” and thus had to cut our convo short (lest he acquire too much dopamine) — Janey Muñoz (@jnymnz) October 1, 2019

For about four years now, the internet has been slowly filling with articles and blogs and dopamine fast diaries by converts who say that abstaining from life is the key to living well. Like intermittent fasting and other biohacking techniques popular in Silicon Valley, dopamine fasting is essentially an effort to optimize yourself so you can concentrate on optimizing everything else.

The theory goes like this: We’re constantly saturated in the neurotransmitter dopamine, every “like” and retweet and bite of cake training our brains to live for the chemical’s impact. Taking a break from anything that might excite us allows our brains to recalibrate and our dopamine dependence to wear off, which leads to more focus and taking more joy from simple stuff.

But while it’s true that dopamine is linked to reward-motivated behavior — addictive drugs, for instance, boost its release — the science behind the dopamine fast trend isn’t really there, says Dr. Joshua Berke, a neuroscientist at UCSF who studies the brain chemical.

“I think it may involve a misconception of what dopamine does for you. Dopamine is not a pleasure juice,” says Berke. “It’s also not the case that dopamine is something that just has a level and that you deplete it. The dopamine dynamic is changing moment to moment.”

That’s not to say there aren’t activities that might throw the system out of whack. Cocaine, for instance, can lead to highs that take a while for the brain to recover from. But sex, exercise or eating a good meal — those are all perfectly fine.

“Normal, pleasurable activities are not doing anything bad to your dopamine system,” Berke says. “Eating good food, talking with friends, there’s no reason to think you need to put a hold on them to keep on enjoying them.”

That’s not to say the general practice of limiting stimulation is altogether worthless.

“The academic discussion around dopamine is missing the forest for the trees,” says San Francisco clinical psychologist Cameron Sepah. In August, Sepah penned a LinkedIn blog post outlining his own approach to dopamine fasting and calling it the “hot Silicon Valley trend.” The essay, he says, has been viewed 130,000 times.

The practice, he says, is somewhat misunderstood. “The focus is on problematic behaviors, not dopamine. Dopamine is just a mechanism that explains how addictions can become reinforced, and makes for a catchy title.”

As Sepah explains it, dopamine fasting is really just another way of describing and structuring a behavioral therapy technique called “stimulus control.” Sepah’s method is less stringent than forms of dopamine fasting that recommend complete societal withdrawal (and drinking only water). Instead, he suggests his patients — among them CEOs and venture capitalists — target specific behaviors that are “personally problematic.” Depending on the patient, those could be things like emotional eating, thrill seeking, gambling, gaming or substance abuse. His technique is also different in that it allows clients to build the fast into even very busy schedules.

“By limiting use within specific time blocks, you are engaging in a time-based stimulus control, which provides structure and reduces impulsive behavior,” Sepah wrote in an email. “In my clinical practice, I find clients report significant improvements in time saved, mood, ability to focus and engaging in other healthy behaviors like nutrition, exercise, sleep and intimacy they have been under-addressing.”

The message clearly resonates. A Nov. 2018 YouTube video by wellness blogger and vlogger Richard Yong, better known on the internet as Improvement Pill, called “How To GET Your Life Back Together - Dopamine Fast” has been viewed 1.7 million times.

To get to the real roots of dopamine fasting, though, you’d have to go back millenia. The term may be new, but the ideas that underpin it can be traced back to silent meditation, specifically the Vipassanā tradition, which itself has found a foothold among Silicon Valley elite who look to 10-day silent meditation retreats for a “reset.”

For my birthday this year, I did a 10-day silent vipassana meditation, this time in Pyin Oo Lwin, Myanmar . We went into silence on the night of my birthday, the 19th. Here’s what I know — jack (@jack) December 9, 2018

“Dopamine fasting is basically just an easy mode version of a Vipassanā retreat,” says Yong. “I basically tried it out, found that it worked and decided to make a video about it one day.”

He was in one of those ruts, the sort “where we’re doing nothing, we’re eating junk food, watching Netflix and we’re like ‘Oh my, God. What am I doing with my life?’”

Since he was doing nothing, he figured, “I’m going to double down on doing nothing” — one day of no food, phone, TV, internet, books, talking or substances. Basically, “having as little fun as possible.” The experience was boring, but effective. But by the end of the day, he was ready to get his life together. “After a day of doing nothing, everything seems more fun.”

The viral response, particularly from people in Silicon Valley, caught him off guard. “I didn’t think people would take it so seriously,” Yong says. But in retrospect, it makes some sense. “Everyone in Silicon Valley wants that 5, 10% slight edge.”

He describes a dopamine fast as a “cheat code” or a “reset button.” Something you use when things freeze up or you need an assist. For a while, Yong would do the fast a couple times a year, usually on his birthday and New Year’s Day. But these days he doesn’t have to implement the draconian day off very often.

“I’m more grown up now,” he says. “I’ve gotten in the habit of working on my projects.”

Ryan Kost is a San Francisco Chronicle staff writer. Email: rkost@sfchronicle.com. Twitter: @RyanKost