SAN FRANCISCO — Everything was going really well for the men of Tennessee Street. Women wanted to talk to them, investors wanted to invest, their new site got traffic, phones were buzzing, their Magic: The Gathering cards were appreciating. This all was exactly the problem.

They tried to tamp the pleasure. They would not eat for days (intermittent fasting). They would eschew screens (digital detox). It was not enough. Life was still so good and pleasurable.

And so they came to the root of it: dopamine, a neurotransmitter that is involved in how we feel pleasure. The three of them — all in their mid-20s and founders of SleepWell, a sleep analysis start-up — needed to go on a dopamine fast.