May didn't notice much with the first dose of LSD. She felt good, and she got a lot accomplished, and that was all. 

It was the day after that things really clicked. She felt even better, and she got a lot more accomplished. She repeated this pattern for a month — one 10-microgram dose of LSD every fourth day — as per the regimen recommended by psychologist and microdosing research pioneer James Fadiman's protocol, made mainstream-famous by Ayelet Waldman's monthlong LSD self-study chronicled in last year's A Really Good Day.

"I did a little experiment," says May, a 64-year-old psychotherapist in Marin County requesting anonymity. "It was this game on my iPad that I was kind of stuck on, and I noticed that whenever I was on day two of the microdosing [regimen], my performance was significantly better."

This wasn't May's first time doing acid. She'd taken LSD (full name: lysergic acid diethylamide) sporadically over the past 40 years. This was, however, her first foray into microdosing. She'd heard promises that microdosing LSD would yield heightened productivity and dissipate mental clutter.