Before he began hosting “All In,” which airs weeknights on MSNBC, Chris Hayes was already something of a multiplatform brand. There were bylines in progressive magazines like In These Times and The Nation, stints subbing for Rachel Maddow and other future MSNBC colleagues, a well-received book about meritocracy in America, an energetic Twitter account, and, of course, “Up,” where Mr. Hayes moderated brainy political debates for the network’s weekend-morning audience.

Now the youngest face of the network’s prime-time block, and the recent winner of his second Emmy, Mr. Hayes finds himself confronting the private and public demands of the cacophonous media-political environment in which he plays a leading role. He fears missing bedtime for his three children, and worries about “the ungodly amount of caffeine” he consumes. Twitter, he says, “feels like smoking three packs a day.”

The steady disintegration of New York City’s subway system, which he took while growing up in the Bronx and rides to work each day, is particularly troubling: “There’s literally nothing more important to the functioning of New York than public transit!”

Such anxieties are difficult to separate from Mr. Hayes’s appeal to the left-leaning audience of MSNBC, his engaged Twitter followers and his growing bookstore crowd. (His second title, “A Colony in a Nation,” was published last year.) Mr. Hayes won’t necessarily dispel anxiety about the future of the Metropolitan Transportation Authority, or of human civilization. But he recognizes the nature and magnitude of the concern, and the impatience of those, including himself, who want to do something about it. We connected in early October.

9 a.m. Wake up at our house in Ulster County.

10 a.m. Go for a nice walk and am convinced by the kids to take them off the trail, resulting in me wiping out into a mud puddle. Get lots of looks as we walk around.

1:30 p.m. Pass out during car ride back to Manhattan. Begin to worry that this diary will expose how perpetually under-slept I am.

4:30 p.m. I’m interviewed by Andrew Marantz for The New Yorker Festival. I’ve done dozens of these kinds of events, and this might be my favorite.

6 p.m. Grab drinks with Andrew and my editor at Norton, Tom Mayer, in Hell’s Kitchen.

7 p.m. Call an Uber to head home because the M.T.A.’s weekend service suspensions are madness, but traffic is so bad that I regret it. Every time I take a mode of transit in this city, without fail, I feel like I made the wrong choice. Getting around the city on the weekends has become impossible, too. My life is an unceasing festival of impatience.

8 p.m. Traffic is terrible and I’m now stressing that I’m going to miss bedtime, and I only a get a few nights a week to do it!

7 a.m. Wake up when our youngest, Anya, wakes up. Check Twitter. The site is a pretty central part of my work, in terms of synthesizing the sheer amount of information that I need to do “All In.” Of course, I tell myself it’s for work, but it also sometimes feels like I work for a tobacco company and I’m smoking three packs a day, telling myself, “I have to be in touch with the company’s product!”

9 a.m. Start to plan the week ahead. I don’t really go into weeks with any grand themes or narratives. One thing I’ve learned the hard way is you can’t get too attached to stories or set pieces in this news environment because things keep happening: It’s more like an improv than a three-act play.

I do, obviously, have a bead on the main stories of the week, like Jamal Khashoggi’s murder and the midterm elections. I also have a sense of building narratives: the idea that Brett Kavanaugh’s confirmation had provided a big electoral boost to Republican candidates and the conservative meme that the left had been taken over by “mobs.” I often think about how we’re telling stories in relation to those larger narratives, particularly when I think they’re baseless or wrong or dangerous.

10 a.m. Continue to read up about climate, the history of the U.S. Senate, and a new intellectual history of emotions and politics, called “Nervous States,” that my agent gave me. I subscribe to a bunch of newsletters but don’t really read them; a producer assembles a note every morning that’s like an in-house newsletter that I read instead.

12:30 p.m. Head to work. Commute on the F train is blessedly smooth. Listen to the final episode of Slow Burn’s second season. (I don’t listen to music, actually. When I’m alone, I listen to podcasts.)

1:30 p.m. Meet with staff to plan for tonight’s show. “All In” is divided into segments: A block, B block and so on. For each one, a segment producer will start with a bulleted list of “ingredients”: news developments, audio and other bits of data. After running through the list, the producer uses a phone to record me while I talk through my sense of how the segment could go.

My colleagues will offer their ideas about order, narrative arc and other things we may have missed and omitted. Once we’ve talked through the introduction, we discuss who the guests are and what we want to do in the interview: what questions we want to explore, what conversational areas we want to bring up, and pieces of sound or quotes or data that we might throw in. We do that for each segment, usually in the same order as they’ll air. Then the segment producers begin writing scripts, which I review a few hours before the show begins.

5 p.m. Segment meetings wrap up. I’m, um, fasting today, so am subsisting on caffeine and gum.

8 p.m. Show time. Feel a bit lightheaded from the fasting, but persevere.

10 p.m. Get home and catch up with my wife, Kate, who has the stamina and focus of a futuristic robot and is able to put in like three hours of work after the kids’ bedtime. I’m basically a brain-dead mess, but catching up with her, just the two of us, is always one of the best parts of the day.

6 a.m. Wake up when our son, David, crawls into bed with us. Make breakfast for the kids with my father-in-law, who’s staying with us for a few days.

9 a.m. Walk David to school while trying and failing to explain evolution, a topic he’s obsessed with but currently a little hazy on. Hard to make the distinction between individual monkeys turning into individual humans and the evolution of an entire species.

1:30 p.m. Meetings for tonight’s show. I’m currently at inbox zero, although I have thousands of unread messages in other folders.

7:45 p.m. Leave office for hair and makeup, which takes a minute to walk to and usually 10 minutes to finish. Currently running on six or seven cups of coffee, or about 12 servings. “Up,” my former show, was much easier and much more natural and authentic to my default mode of address and style of conversation. I think I actually enjoyed the doing of that show more, though “All In” stretches me in all kinds of ways that “Up” didn’t.

9 a.m. Have a lovely school drop-off with my two older kids. Spend the whole time fantasizing about what dog we might get someday. (Four years from now is the opening bid.) Afterward, I see my therapist, visit my friends’ 7-week-old, grab breakfast and head to the gym. Afterward, I’m dragging and the caffeine receptors in my brain are feeling like stripped screws.

1 p.m. Arrive at office, where I have a sitting/standing desk, but I’m too lazy to actually stand at it. I wear Bose noise-canceling headphones, which are amazing, and so large they are hard to lose. For writing, I use Scrivener to keep my research, notes and other references in one easily searchable place, and Freedom to limit online distractions. I rely on TeuxDeux for to-do lists. I also have an incredible assistant, Aileen Normile, who helps manage my schedule.

1:30 p.m. Segment meetings, where I confer with the line producer Tiffany Champion, the senior producers Brendan O’Melia and Tina Cone, and the executive producer Denis Horgan. Lots of hurricane coverage planned for tonight.

9 p.m. Head home.

7 a.m. Wake up and check Twitter, which feels a bit like walking into the lobby of a Las Vegas casino at 6 a.m. to head to the airport and seeing all the people, dead-eyed, playing the slots: They’ve either been there all night or they woke up and started playing slots first thing in the morning.

1:30 p.m. Meeting with my staff.

3 p.m. Pull day at the gym. Since February, I’ve been working out with a trainer three days per week. I don’t want to name the gym I attend, for privacy, but it’s in Manhattan on my way to work.

7 p.m. I truly worry my brain chemistry has been permanently altered for the worse by constant stimulus.

12:30 a.m. Go to sleep. No work tomorrow, since it’s my day off. I very rarely have Fridays off. This was a special case because I had worked a few weekend days in a row, and I’d put in a request for it ahead of time.

Interviews are conducted by email, text and phone, then condensed and edited.