The original tweet before it was deleted and its author. White House press secretary Sean Spicer suggested the typo was intentional, telling reporters, "a small group of people know exactly what he meant". It may not be a temporary phenomenon, a new study in the Journal of Neuroscience suggests. Chronic sleep deprivation in mice causes microglia - brain cells that get rid of toxins and clear debris - to eat small pieces of the synapses, the connections that allow neurons to communicate with each other, the study found. It did not mention Trump. If this activation is prolonged, it could "trigger a chain of events" that leads to cellular degeneration, which is related to cognitive impairment, say neuroscientist Chiara Cirelli, who led the research. Sleep is "very, very important" to normalise the functions of the brain's synapses, she said. "I don't think we know of any cognition function that isn't affected by sleep deprivation," added Cirelli, a physician who directs the Wisconsin Centre for Sleep and Consciousness and is a professor of psychiatry at the University of Wisconsin-Madison's medical school. She cites effects on working memory, the "capacity to integrate a lot of information and even appreciation of humour".

Trump's press secretary Sean Spicer said some knew what Trump meant by covfefe Credit:Bloomberg Asked if she thinks about this when seeing and reading about Trump, Cirelli noted, "I cannot not think about this". Mark Bertolini, cheif executive of Aetna, a healthcare company, takes sleep so seriously the company pays employees up to $US300 ($400) a year if they regularly sleep at least seven hours a night as shown on their tracking devices. The trick is to make sure you get enough sleep, says Arianna Huffington. Trump's latest questionable tweet, about three days after he returned from a nine-day, overseas trip, was a sign Trump could be suffering from jet lag or may have even nodded off at the keyboard, Winter says.

White House Chief of Staff Reince Priebus told reporters on Air Force One on the way to Saudi Arabia that the President didn't get much sleep on the flight. In his speech in Riyadh, Trump departed from his prepared remarks, saying "Islamic extremism" instead of the more carefully crafted phrase "radical Islamist extremism". Early on Wednesday, Twitter night owls in the US and others around the world wondered what explained the lack of a follow up post until six hours later, when the typo-tweet was deleted and replaced by one making light of his misspelling. Some of Trump's most memorable tweets have been even later at night - or earlier in the morning, depending on one's schedule. It was 2.30am September 30 when he tweeted about a former Miss Universe contestant he knew who had started campaigning with his opponent, former secretary of State Hillary Clinton. He suggested his tens of millions of Twitter followers "check out sex tape and past" and asked rhetorically if Clinton had helped her become a citizen. At 3.40am on August 7 Trump said then-Fox News host @megynkelly "really bombed tonight".

He can be more civil after sunrise (in the East). At 6.40am on February 15, the media was "going crazy with their conspiracy theories and blind hatred," Trump tweeted. Last week, the Chicago Tribune started an article about Trump's first foreign trip with: "He stifles yawns. His eyes narrow. And ultimately, when he garbles part of his speech, an aide explains that President Donald Trump is 'just an exhausted guy'." "Sleep evangelist" Arianna Huffington has been using Trump as her highest profile argument for a good night's sleep since her Colby College commencement speech last May. Well-known to be liberal, Huffington is an equal-opportunity sleep critic. She has compared Trump's erratic and occasionally questionable behaviour to that of former president Bill Clinton, who also boasted about how little sleep he got when he was president. "Mood swings, fogged memories, incomprehension of a comprehensible problem and the occasional re-tweeting of Mussolini," Huffington told Colby graduates, according to an article on CentralMaine.com. "These are all symptoms of chronic sleep deprivation, according to the American Academy of Sleep, except the re-tweeting Mussolini part - that's just pure Donald Trump."

Huffington, author of The Sleep Revolution, is especially critical of Trump and others who brag about sleeping little and compares sleep deprivation to being drunk. "I've never smoked a cigarette in my life," Trump told Rolling Stone in 2011. "I've never had a drink, never had a joint, never had any drugs, never even had a cup of coffee." He did confess to liking a "little caffeine", noting that "Coke or Pepsi boosts you up a little". The habit continues. In April, the Associated Press reported Trump pushed a red button that presidents have long used and a White House butler brought Trump a Coke. Jet lag like 70-year-old Trump may be experiencing "is harder on older adults", Winter says. He personally slept three to four hours a night during his medical residency, but says that took a toll on his health as he was eating poorly and not exercising, which he says could also describe Trump. "It's not that you can't, it's that you don't want to be in that situation if you're taking a spleen out -- or [if you are] the leader of the free world," Winter says.

Other possibilities Winter cited for Wednesday's tweet was "micronaps" which occur when people fall asleep for short periods of time but don't realise it or inattentiveness, seeing Trump's tweet wasn't finished or immediately followed up. In her new study, Cirelli says the mice were kept awake for about seven additional hours for five days with "novel objects to keep them interested. They stay awake playing. It's not too difficult". Loading Sleep researchers have used animals to demonstrate that the neurons in the brain can take five or ten minutes or as long as an hour to get to "full wake performance", she says. "I have learned that certainly applies to me. I never send any email for at least two hours after I wake up because sometimes I make huge mistakes. That's my rule."

USA Today