OpenAI CEO Sam Altman's Daily Routine: 15-Hour Fasts and Low-Dose Sleeping Pills An after-lunch espresso is a must.

^{This article originally appeared on Business Insider.}

Sam Altman has returned to his position as CEO of OpenAI after a chaotic few days of management reshuffles at the company thrust him further into the spotlight.

But outside the office, Altman is one of many tech execs obsessed with extending his lifespan. He has also reportedly prepared for doomsday scenarios (including the chance of a lethal synthetic virus being released, nuclear warfare, and AI attacks) with a stash of guns, gold, and survival supplies. Whether it's sleep, his work schedule, or diet, he's particular about many aspects of his daily life and maximizing his effectiveness.

Here's a look at some of Altman's habits. He has not responded to Business Insider's request for comment.

Mornings:

Altman drinks a large shot of espresso immediately after waking up, but otherwise rarely eats breakfast, he wrote in 2018. He said he typically fasts for about 15 hours most days as a result.

While catching up on emails, he uses a full spectrum LED light most mornings for about 10 to 15 minutes — a "ridiculous gain" for him.

He also said he avoids scheduling early meetings since that's when he's the most productive.

Work days:

Altman prefers taking his appointments in the afternoon but has an unconventional attitude toward carving out space for them.

"I find most meetings are best scheduled for 15-20 minutes, or 2 hours," he wrote. "The default of 1 hour is usually wrong, and leads to a lot of wasted time."

Broadly speaking, though, he avoids them as much as possible, finding work in his office more valuable.

"90% of the random meetings I take are a waste of time," Altman wrote, though "the other 10% really make up for it."

Instead, he prioritizes leaving space in his schedule to "allow for chance encounters and exposure to new people and ideas," and also to think about what to work on.

Altman uses a lot of lists for organization but prefers to make them on paper rather than digitally.

They track "what I want to accomplish each year, each month, and each day," according to his blog. "Lists are very focusing, and they help me with multitasking because I don't have to keep as much in my head. If I'm not in the mood for some particular task, I can always find something else I'm excited to do."

He also drinks another shot of espresso after lunch.

Nights:

Despite the caffeine, sleep is one of the most important things Altman said he needs to be productive. He avoids eating too much before bed, and finds skipping alcohol also helps.

He's been a vegetarian since he was a child, and drinks protein shakes frequently to supplement his diet — though said he hates them. He tries to avoid inflammatory foods, like very spicy dishes or anything that might "aggravate" his digestion, and also tries to avoid eating too much sugar. Still, he doesn't "have much willpower when it comes to sweet things."

He also said that quarterly blood testing has helped him supplement his diet with a range of vitamins, and reportedly takes the diabetes drug metformin to slow down aging.

When he goes to bed, Altman uses a sleep tracker and prefers a "cold, dark, quiet room" with a good mattress. If he's not chilly enough he uses a cooling pad and often takes a low dose of either sleeping pills or cannabis to help him sleep.

Exercise:

Altman favors lifting heavy weights three times a week for an hour, and high-intensity interval training occasionally, having tried a variety of options. "In addition to productivity gains, this is also the exercise program that makes me feel the best overall."