Diane does not look like someone who would drug your venison chili. She sits on a San Francisco patio, her dewy blue eyes lucid, her blonde, subtly asymmetrical hair recently trimmed, her white jeans spotless. It is noon. I imagine she has enjoyed several fruitful meetings. Now, she will probably advise me on the meditation app keeping her serene.

“I don’t do coffee, I do acid,” she says. The declaration that she takes a Class A drug does not distract her from nibbling a chunk of salmon in her taco bowl. The 29-year-old start-up founder began microdosing LSD — tiny doses every few days — in January. At just a tenth of a tripping dose, she does not experience psychedelic effects. Rather than swirling in a magical universe with pink elephants, she says microdosing has improved her productivity, creativity and helped her focus. On LSD, she is able to concentrate when developing company strategy, speed through user design sessions and sparkles making new contacts.

“When I’m microdosing at networking events or social happy-hour mixers, they go well. I have really good conversations as I am that little more ‘on’, more focused on what the person is saying. It enhances connections and heightens empathy,” she explains.

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Diane is part of a new generation of LSD users who believe it is a useful and harmless enhancement, like meditation or coffee. They meticulously plan regimes, often taking 10 to 20 micrograms every three days. There is little research on microdosing, so they track how their bodies and minds respond, submitting reports to researchers and discussing effects with almost 18,000 other microdosers on Reddit.

Fifty years after the Summer of Love, they disdain their predecessors’ Acid Tests — in the mid-1960s Ken Kesey’s Merry Pranksters took huge doses and even spiked venison chili or Kool Aid with the drug — viewing them as rash and reckless. The generation obsessed with making every hour count, embracing Marie Kondo-style tidying binges and “inbox zero” email-clearing parties, is now co-opting psychedelics into its mission.

“It’s a sign of the times,” says Diane. “LSD is a very flexible substance. It amplifies whatever is happening in your brain. It is amplifying whatever is happening in our society. We are all productivity-obsessed, so that’s our usage of it.” Silicon Valley’s microdosers want to overcome the drug’s notoriety, harnessing the tech industry’s talent at transforming global habits to make the psychedelic as acceptable as coffee.

San Francisco became the acid capital of the world in the 1960s, when hippies, inspired to alter their consciousness by Buddhists and Native Americans, ran wild. Now, the city is spearheading the microdosing movement, with tech workers taking their cue from Steve Jobs, Apple’s co-founder, who said LSD was one of the “two or three most important things” he did in his life. While some, like Jobs, take full-blown trips, increasingly LSD is consumed in doses where the effects are subtle and do not interfere with everyday life. Several of Diane’s friends started microdosing this year. Tim Ferriss, tech investor and author of the Four Hour Work Week, has said almost all the billionaires he knows regularly take hallucinogens.

The FT spoke to several microdosers, all of whom asked to withhold their real names because the drug is illegal. All highly motivated professionals, most work in the tech industry, often leading their own start-ups. They all reported using LSD as a tool to boost productivity under pressure, to invent the cascade of ideas demanded from knowledge workers, and to improve their focus in a world filled with distractions (often created by the tech industry).

“Being a CEO is so unbelievably demanding, you need to be superhuman,” Gail, a 31-year-old start-up founder, tells me on a bench in South Park, an elegant San Francisco square favoured by venture capitalists. Taking LSD helps her keep calm. “As an entrepreneur, you are rejected by investors all the time. Things are not working all the time,” she says.

Paul, a start-up founder in New York, says he and his employees are less stressed since they started microdosing. But he couldn’t be absolutely sure about the cause and effect: he thinks it may have also been the project-management app Asana, which they started using at the same time, to keep organised.

Others self-medicate with LSD to treat mental-health problems, such as depression. Chantelle, 35, a food entrepreneur, was reluctant to turn to conventional antidepressants. In a private members’ club in San Francisco, she whispers that the awareness she felt while microdosing was “amazing”. “It was almost like being your own therapist.” Even when she didn’t microdose for weeks, her mood was “extremely stable”. “If I did have a breakdown, it lasted like five minutes and I was done. Before, it would be two or three days in bed.”

LSD is not the only drug experiencing a revival. Studies are investigating if psilocybin, the active ingredient in magic mushrooms, can be used to ease “end of life” anxieties in terminally ill patients, and whether MDMA can be used in therapy to relieve post-traumatic stress disorder. Some tech workers are making pilgrimages to South America to take ayahuasca, said to give deep insights while making you vomit prolifically.

Many microdosers are horrified by how the hippies abused LSD. They believe the Summer of Love set back understanding of the drug, as little research on its effects has been done since. Diane says it was “ethically wrong” and “real violence” to drug people without their permission, as occurred in some of the acid tests. Paul Austin, 26, founded The Third Wave organisation to encourage the cultural acceptance of psychedelic use. The first wave of psychedelics, he believes, was traditional use by native peoples from Ancient Greece to India. They were made illegal after the second wave in the 1960s, as parents panicked about tripping teenagers. Now, in the third wave, he believes that microdosers can undo the damage done by the baby boomers and make LSD legal again.

Dr Molly Maloof, a young doctor with many patients who are Silicon Valley executives, says she has observed an increasing interest in “biohacking” — the idea that individuals can develop the best possible version of themselves, using a combination of vitamins, exercise and drugs. Maloof cannot prescribe illegal drugs, but does advise patients who microdose on harm reduction. She believes that the future for psychedelics is “bright” — and that they could be legal within five to 10 years. “The hippie 2.0 generation is turning LSD into people pursuing their purpose and their highest potential, not wanting to go out and party and go crazy,” she says.

Fifty years ago, Boots Hughston was 18 and lost. Driving in circles around the Panhandle, a stretch of grass below Haight Ashbury, he and his friends were searching for the “Human Be In”, about a mile away in Golden Gate Park. It was early 1967, months before images of San Francisco’s flower-wearing, LSD-taking hippies enjoying the Summer of Love were beamed across the world.Timothy Leary, the psychedelics pioneer, rallied tens of thousands at the event with his now famous instruction to “Turn on, Tune in, Drop out”. Hughston arrived late and followed the crowd to watch the sunset at the beach. There, he shared a joint with Leary, the former Harvard psychologist who President Richard Nixon once described as the “most dangerous man in America”.

“[Leary] was touting acid at the time,” Hughston tells me. “He said something like, ‘That’s a pretty nice sunset, pretty wild. Don’t you realise it’s the only time you’ll ever see it?'” Hughston went on to take LSD 20 or 30 times — and learnt the importance of measuring doses the hard way. “One time, everything was just melting all around me,” he says, describing a Grateful Dead show on New Year’s eve. “One of the artists had a bottle of wine with a whole bunch of doses of acid in. The tabs were all at the end of the bottle, so my swig was mostly tabs. I got a little higher than I probably should have . . . It was three or four days, or a week, to get myself back together.”

Today’s microdosing culture illustrates how the residents of San Francisco have moved from dropping out to climbing the career ladder; a transformation that has dispirited the city’s old hippies. Where the Diggers, a group of performance artists-cum-charity workers, once gave out free food in the Haight, tech workers today pursue stock options to pay for $10 toast and $1m apartments. Where art, music and fashion used to blossom, boutique exercise studios and green juice makers attempt to fill a cultural vacuum.

“As an artist, you could live an existence pretty well. You wouldn’t be hand to mouth,” says Hughston, whose friends shared apartments paying $20 a month each, eating vegetables, fruit and brown rice provided by The Diggers. “Nowadays, it is $4,000 a month for a one bedroom. It’s crazy, you can’t just go out and hang out with your buddies, work on your art. You have to make a living, get a job that pays real money — and fit in.

“Hughston still doesn’t want to fit in. He has been battling for the right to memorialise the Summer of Love in Golden Gate Park — a plan that has been rejected three times. One morning in June, he and his entourage of grey-haired hippies — known as the “Council of Light” — filled a room at San Francisco’s City Hall to plead with the park’s department for permission. The department claims they are ill-prepared (objections included impractical plans to put Portaloos on the flowerbeds), despite the group having organised concerts for the 40th anniversaries of the Summer of Love and Woodstock.

The tie-dyed crowd see the department’s intransigence as a rejection of their values, in favour of events organised by corporations. Hughston is convinced that the permits officer does not like “hippie events”. “I’ve done many shows there before with no problems at all, so they can’t really say there’s going to be a bunch of people tripping,” he says. “We’re 60, 70, 80 years old — we know how to take edibles without ending up in hospital.”

But the hippies’ frustration goes far beyond this year’s memorial event. They worry that the San Francisco they made famous is losing its values. David Talbot, author of the 2012 book Season of the Witch, which looks at the evolution of San Francisco in the 1960s and 1970s, mourns the loss of the city to the techies.

“The earlier social invasion of the city was all about expanding the idea of humanity, of what compassion is, things that later became San Francisco values,” he says. “Now it is like the old Gold Rush days in the 1840s. People are basically motivated by greed. People are coming to this city not so much for the kind of enlightened and benevolent and even revolutionary ideals, but to get rich quick.”

Talbot describes San Francisco as a “playground” for companies like Uber and Lyft, whose ride-sharing cars have taken over the roads, with Airbnb colonising neighbourhoods. Everyone is asleep by 10 o’clock. “There is no vibrancy,” he says. “They go to bed. It’s all work-orientated.”

Hughston gave up his dream for a reunion of hippie elders in early July. “This event would have been something our great city would have been proud of,” he wrote to City Hall. “Thru [sic] the eyes of the world; San Francisco would have been seen as the progressive city it once was.”

While the hippies were colonising Golden Gate Park in the 1960s, Jim Fadiman was among a small group of researchers already looking at how LSD could help people become more productive. Today he is revelling in his niche becoming more mainstream. This April, he spoke to an audience of 600 at a bustling psychedelics conference in the Bay Area. He started by asking: “Who here has microdosed?” Hands shot up. Only three or four had not. Leary was dubbed the pied piper of psychedelics; Fadiman is now the pied piper of microdosing. He created the regimen used by many microdosers — 10mg of LSD every three days — in his Psychedelic Explorer’s Guide in 2011. He now receives daily mood surveys and monthly reports from 1,800 microdosers.

This anecdotal research is the closest we have to evidence of the effects of microdosing LSD. Fadiman excitedly claims a wide range of positive impacts unusual for any single drug: from squashing the impulse to procrastinate to easing painful periods. But it is far from a large randomised control trial. With anecdotal reports, Fadiman relies on subjects to accurately self-report their experiences. He cannot compare these effects to a placebo or check the exact dose and purity of the LSD.

In the early 1960s, Fadiman worked at the International Foundation for Advanced Study with Myron Stolaroff, studying whether LSD could help generate new ideas. Stolaroff, an engineer at the tape recorder company Ampex, had discovered that LSD made him sharp and inventive. But Ampex refused to incorporate LSD into their product design process, so he left to start the Foundation. Between 1961 and 1965, the pair experimented on hundreds of scientists, researchers, engineers and architects, to see if they could solve difficult problems while taking the drug.

Many of the subjects had never heard of psychedelics. They were told that it was a chance for “heightened creativity” and totally safe. In the morning, they took full doses of LSD, and were invited to lie down while music played.”

An architect said he really gave himself a world tour of architecture, visited the Pyramids, the Great Wall of China, the Eiffel Tower . . . He was able to travel and see things more visibly than he thought would be possible,” Fadiman tells me. In the afternoon, work began: “When he came to his task, which was a small shopping centre, he said he just felt he was very, very excited by architecture.”

After months of disappointing the client, the architect had a vision of the building so complete he could see how many spaces there were in the car park and the size of the bolts holding the beams together, Fadiman reports. And when he drew the design, the client finally liked it.

In other cases, a scientist came up with a theoretical paper on photons, and an early designer of circuits in semiconductors said he was able to lay out the board in his mind and watch electricity surging through it to see where it broke.

The International Foundation for Advanced Study was shut down when LSD became illegal in California in 1966, the same year the US government banned manufacture or sale of the drug. Two years later, possession of LSD was also outlawed by the federal government.

John Markoff, a former technology correspondent for The New York Times, wrote about the early experiments in What the Dormouse Said, his book on the relationship between the 1960s counterculture and the PC industry. He is a sceptic, believing that LSD was not a “magic pill” that made the era creative.

Instead, he believes that it was probably caused by living on the “edge of chaos” in the 1960s. With today’s Silicon Valley far from the edge, he believes it is no longer taking the creative leaps it took to create the building blocks of computing. “It is pretty tame,” he says. If the tech industry feels the need for enhancements, what about the industries which are being disrupted by tech? Could workers from finance to retail use LSD to keep up?

Before we all start taking a daily dose of the drug with our breakfast, scientists need to understand more about it. It has been more than 70 years since Albert Hofmann, a Swiss chemist, accidentally discovered the psychedelic properties of LSD, a drug developed from compounds in ergot, a fungus that attacks rye. But because of criminalisation, we have little evidence of how it affects the brain, side effects and the potential for any long-term damage.

The US Drug Enforcement Agency says LSD has a “high potential for abuse”, but does not specifically address microdosing. The DEA warns that LSD impairs users’ ability to make sound judgments, making them susceptible to personal injury. Users can suffer “acute anxiety and depression” for days and even months after a trip. Overdose effects include psychosis and possible death.

DrugWise, a UK non-profit organisation that provides advice on drugs, says there is no evidence of people overdosing on LSD, but that fatal accidents have happened to people while taking the drug. It also warns that it may have implications for people with a history of mental-health problems.

The most significant breakthrough in our understanding came last year with the first ever brain-imaging study of people tripping on LSD. The study was led by Professor David Nutt of Imperial College London, who was dismissed as an adviser to the UK government in 2009 for criticising policy on drug classifications. The study found that LSD makes the brain much more connected and flexible, with the visual cortex connected to every part of the brain. It also showed a decrease in blood flow to the “default mode network”, meaning there was less activity in the area that is activated when the mind is wandering, not committed to a task, and thinking about one’s self and one’s emotional state.

Barbara Sahakian, a professor of neuroscience at Cambridge, says there is evidence to support the microdosers’ theory that LSD improves creativity. “LSD at low doses may produce mood elevation and creativity, primarily by mimicking the effects of serotonin, the chemical in the brain that regulates our mood,” she says. It also increases levels of glutamate, which plays a role in learning and memory.

But she warns against buying the drug on the black market, where users have no idea what concentration it is or what it is cut with.

Sahakian studies the impact of so-called “smart drugs” such as Modafinil, used to improve performance, and is concerned about the rate of people turning to drugs to boost their productivity, rather than to natural stimulants like exercise. “What is the pressure going on here that everybody needs to do this? People are worried about losing their jobs, worried about competition,” she says.

One of the greatest risks associated with LSD use is, of course, prison. In the US, LSD is a Schedule I drug. Possession of enough for a hundred microdoses carries a minimum penalty of five years in prison and a fine of up to $2m. In the UK, it is Class A and possession can be up to seven years in prison or an unlimited fine. Many of the microdosers I spoke to obtain their LSD from drug dealers with whom they have a personal connection, and those dealers source it from chemists who manufacture it themselves. Some rely more riskily on the dark web, ordering the drug from an unknown source to be delivered to their house.

The culture of the tech industry encourages experimentation, even if that pushes beyond the boundaries of the law. Silicon Valley’s libertarians see it as part of their quest for “cognitive liberty”.

“The most successful companies like Airbnb and Uber have given the middle finger to the regulators. There’s a sense that the regulations will catch up,” Gail says optimistically.

Even if Silicon Valley makes LSD culturally acceptable, it is doubtful that President Donald Trump, with his conservative base, will legalise the drug. Like cannabis, it may be up to individual states to pursue legalisation, or other countries following Portugal’s decriminalisation of all drugs.

Behind a Saxon hunting lodge with three moats, I sit with Amanda Feilding at a garden table shaded by a large tree. In Oxfordshire, far from Silicon Valley, the Countess of Weymss and March is plotting the future of microdosing. Feilding enthuses as she shows me pictures of the brain lit up on LSD; pictures that also excited many microdosers I met in San Francisco. She points at the explosion of colour in the brain on LSD, compared to scattered patches of orange on a placebo. “There’s just vastly more communication,” the 74-year-old exclaims. “It kind of describes why there’s more feelings, more memories associated with communication, more richness of colour, more richness of hearing, a deeper kind of perception.”

Feilding has been experimenting with ways to expand consciousness since she left school at 16 to study mysticism. Her most radical and famous attempt was trepanation: cutting a hole in her own skull. Feilding first used LSD in the 1960s. She found it could help her concentrate: on high daily doses she could race through the complete works of Nietzsche and Freud, as if “higher up the mountain”.

Since the 1990s, she has worked with scientists to explore drugs research with her organisation, the Beckley Foundation, which partnered with Dr Nutt at Imperial to conduct the LSD brain-imaging study. Now she plans to lead a study into the effects of microdosing LSD, working with Nutt and his colleagues again, and potentially other institutions including NYU. Nutt will shortly begin seeking ethical approval for the study in the UK. The participants will complete cognitive tests used to track depression and anxiety, and have their strategic abilities tested by playing Go, the complex Chinese game that Google is using to train artificial intelligence. “Could LSD enhance our most human skills like creativity, while artificial intelligence takes over our more robotic tasks?” I ask, thinking of another Silicon Valley obsession. “Absolutely, I totally agree with that,” she says.

If positive outcomes can be shown for patients with depression, she would like to push towards legalisation — and eventually regulated access for non-medical uses. “We’ve lost 50 years through criminalisation. It was a lousy, ignorant reaction, based not on scientific evidence but prejudice, media coverage and false stories,” she says. “When we finally get to the other side and they become regulated, nobody will ever believe they weren’t: it will be just too ridiculous.”

Her biggest problem is funding. Many medical research bodies are cautious about backing a project looking into the positive effects of illegal drugs. Trials using illegal drugs are also more expensive due to detailed requirements on how to store and administer them. So Feilding is turning to Silicon Valley for help. In 2011, her foundation received a donation from Sean Parker, the Napster founder and early Facebook investor, for its drug policy work (though not for research into psychedelics).

Now Feilding is starting a “for profit” arm of her foundation. She hopes tech entrepreneurs will invest to do good and to make money: she believes they could start a business making “wonderful cannabis medicines” and opening clinics. When Feilding describes the science behind LSD, she speaks like Silicon Valley inventors talking about their “moonshots”, ambitious projects such as self-driving cars or private space missions. But microdosing, she believes, could do more for the world than many transformational technologies.

“A happier, more balanced species would do more good than getting us to Mars,” she said. “How can you do more good than trying to solve some of the problems of the human psyche?”