WASHINGTON >> “Are you up?”

The emails arrive late, often after 1 a.m., tapped out on a secure BlackBerry from an email address known only to a few. The weary recipients know that once again, the boss has not yet gone to bed.

The late-night interruptions from President Barack Obama might be sharply worded questions about memos he has read. Sometimes they are taunts because the recipient’s sports team just lost.

Last month it was a 12:30 a.m. email to Ben Rhodes, the deputy national security adviser, and Denis McDonough, the White House chief of staff, telling them he had finished reworking a speechwriter’s draft of presidential remarks for later that morning. Obama had spent three hours scrawling in longhand on a yellow legal pad an angry condemnation of Donald Trump’s response to the attack in Orlando, Florida, and told his aides they could pick up his rewrite at the White House usher’s office when they came in for work.

Obama calls himself a “night guy,” and as president, he has come to consider the long, solitary hours after dark as essential as his time in the Oval Office. Almost every night that he is in the White House, Obama has dinner at 6:30 p.m. with his wife and daughters and then withdraws to the Treaty Room, his private office down the hall from his bedroom on the second floor of the White House residence.

There, his closest aides say, he spends four or five hours largely by himself.

He works on speeches. He reads the stack of briefing papers delivered at 8 p.m. by the National Security Council staff secretary. He reads 10 letters from Americans chosen each day by his staff. “How can we allow private citizens to buy automatic weapons? They are weapons of war,” Liz O’Connor, a Connecticut middle school teacher, wrote in a letter Obama read on the night of June 13.

The president also watches ESPN, reads novels or plays Words With Friends on his iPad.

Michelle Obama occasionally pops in, but she goes to bed before the president, who is up so late he barely gets five hours of sleep a night. For Obama, the time alone has become more important.

“Everybody carves out their time to get their thoughts together. There is no doubt that window is his window,” said Rahm Emanuel, Obama’s first chief of staff. “You can’t block out a half-hour and try to do it during the day. It’s too much incoming. That’s the place where it can all be put aside and you can focus.”

President George W. Bush, an early riser, was in bed by 10 p.m. President Bill Clinton was up late like Obama, but he spent the time in lengthy, freewheeling phone conversations with friends and political allies, forcing aides to scan the White House phone logs in the mornings to keep track of whom the president might have called the night before.

“A lot of times, for some of our presidential leaders, the energy they need comes from contact with other people,” said the historian Doris Kearns Goodwin, who has had dinner with Obama several times in the past 7 1/2 years. “He seems to be somebody who is at home with himself.”

‘An Insane Amount of Paper’

When Obama first arrived at the White House, his after-dinner routine started around 7:15 p.m. in the game room, on the third floor of the residence. There, on an old Brunswick pool table, Obama and Sam Kass, then the Obama family’s personal chef, would spend 45 minutes playing eight-ball.

Kass saw pool as a chance for Obama to decompress after intense days in the Oval Office, and the two kept a running score. “He’s a bit ahead,” said Kass, who left the White House at the end of 2014.

In those days, the president followed the billiards game with bedtime routines with his daughters. These days, now that both are teenagers, Obama heads directly to the Treaty Room, named for the many historical documents that have been signed in it, including the peace protocol that ended the Spanish-American War in 1898.

“The sports channel is on,” Emanuel said, recalling the ubiquitous images on the room’s large flat-screen television. “Sports in the background, with the volume down.”

By 8 p.m., the usher’s office delivers the president’s leather-bound daily briefing book — a large binder accompanied by a tall stack of folders with memos and documents from across the government, all demanding the president’s attention. “An insane amount of paper,” Kass said.

Obama often reads through it in a leather swivel chair at his tablelike desk, under a portrait of President Ulysses S. Grant. Windows on each side of Grant look out on the brightly lit Washington Monument and the Jefferson Memorial.

Other nights, the president settles in on the sofa under the 1976 “Butterfly” by Susan Rothenberg, a 6-foot-by-7-foot canvas of burnt sienna and black slashes that evokes a galloping horse.

“He is thoroughly predictable in having gone through every piece of paper that he gets,” said Tom Donilon, Obama’s national security adviser from 2010-13. “You’ll come in in the morning, it will be there: questions, notes, decisions.”

Seven Almonds

To stay awake, the president does not turn to caffeine. He rarely drinks coffee or tea, and more often has a bottle of water next to him than a soda. His friends say his only snack at night is seven lightly salted almonds.

“Michelle and I would always joke: Not six. Not eight,” Kass said. “Always seven almonds.”

The demands of the president’s day job sometimes intrude. A photo taken in 2011 shows Obama in the Treaty Room with McDonough, at that time the deputy national security adviser, and John O. Brennan, then Obama’s counterterrorism chief and now the director of the CIA, after placing a call to Prime Minister Naoto Kan of Japan shortly after Japan was hit by a devastating magnitude 9.0 earthquake. “The call was made near midnight,” the photo caption says.

But most often, Obama’s time in the Treaty Room is his own.

“I’ll probably read briefing papers or do paperwork or write stuff until about 11:30 p.m., and then I usually have about a half-hour to read before I go to bed, about midnight, 12:30 a.m., sometimes a little later,” Obama told Jon Meacham, the editor-in-chief of Newsweek, in 2009.

In 2014, Obama told Kelly Ripa and Michael Strahan of ABC’s “Live With Kelly and Michael” that he stayed up even later — “until like 2 o’clock at night, reading briefings and doing work” — and added that he woke up “at a pretty reasonable hour, usually around 7.”

‘Can You Come Back Tonight?’

Obama’s longest nights — the ones that stretch well into the early morning — usually involve speeches.

One night in June 2015, Cody Keenan, the president’s chief speechwriter, had just returned home from work at 9 p.m. and ordered pizza when he heard from the president: “Can you come back tonight?”

Keenan met the president in the usher’s office on the first floor of the residence, where the two worked until nearly 11 p.m. on the president’s eulogy for nine African-Americans fatally shot during Bible study at the Emanuel African Methodist Episcopal Church in Charleston, South Carolina.

Three months earlier, Keenan had had to return to the White House when the president summoned him — at midnight — to go over changes to a speech Obama was to deliver in Selma, Alabama, on the 50th anniversary of “Bloody Sunday,” when protesters were brutally beaten by the police on the Edmund Pettus Bridge.

“There’s something about the night,” Keenan said, reflecting on his boss’s use of the time. “It’s smaller. It lets you think.”

In 2009, Jon Favreau, Keenan’s predecessor, gave the president a draft of his Nobel Prize acceptance speech the night before they were scheduled to leave for the ceremony in Oslo. Obama stayed up until 4 a.m. revising the speech, and handed Favreau 11 handwritten pages later that morning.

On the plane to Norway, Obama, Favreau and two other aides pulled another near-all-nighter as they continued to work on the speech. Once Obama had delivered it, he called the exhausted Favreau at his hotel.

“He said, ‘Hey, I think that turned out OK,’” Favreau recalled. “I said, ‘Yes.’ And he said, ‘Let’s never do that again.’”

Some Time for Play

Not everything that goes on in the Treaty Room is work.

In addition to playing Words With Friends, a Scrabble-like online game, on his iPad, Obama turns up the sound on the television for big sports games.

“If he’s watching a game, he will send a message. ‘Duke should have won that game,’ or whatever,” said Reggie Love, a former Duke basketball player who was Obama’s personal aide for the first three years of his presidency.

The president also uses the time to catch up on the news, skimming The New York Times, The Washington Post and The Wall Street Journal on his iPad or watching cable. Love recalls getting an email after 1 a.m. after Obama saw a television report about students whose “bucket list” included meeting the president. Why had he not met them, the president asked Love.

“‘Someone decided it wasn’t a good idea,’ I said,” Love recalled. “He said, ‘Well, I’m the president and I think it’s a good idea.’”

Obama and his wife are also fans of cable dramas like “Boardwalk Empire,” “Game of Thrones” and “Breaking Bad.” On Friday nights — movie night at the White House — Obama and his family are often in the Family Theater, a 40-seat screening room on the first floor of the East Wing, watching first-run films they have chosen and had delivered from the Motion Picture Association of America.

There is time, too, for fantasy about what life would be like outside the White House. Emanuel, who is now the mayor of Chicago but remains close to the president, said he and Obama once imagined moving to Hawaii to open a T-shirt shack that sold only one size (medium) and one color (white). Their dream was that they would no longer have to make decisions.

During difficult White House meetings when no good decision seemed possible, Emanuel would sometimes turn to Obama and say, “White.” Obama would in turn say, “Medium.”

Now Obama, who has six months left of solitary late nights in the Treaty Room, seems to be looking toward the end. Once he is out of the White House, he said in March at an Easter prayer breakfast in the State Dining Room, “I am going to take three, four months where I just sleep.”

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