Her memoir Becoming has sold more than 15 million copies worldwide and was the best-selling book of 2018.
Now Michelle Obama has revealed how she "woke up in a panic" the night before an interview with Oprah Winfrey that was timed with Becoming going on sale and to kick-off a worldwide promotional tour.
In an essay for The Sunday Times' Style magazine, the former first lady, 57, explained how she was scheduled to appear on stage with the legendary broadcaster in front of an audience of 14,000 people at a basketball arena in her home city of Chicago.
She wrote: "I laid awake anxious in my bed."
Obama recalled thinking: "What if the book just isn’t any good? What if people hate it? Or what if they just don’t care at all?"
She explained that her other half, former president Barack Obama, helped comfort her and allayed her concerns that the memoir wouldn't be well-received.
The mother-of-two added: "My husband stays up much later than me, and thankfully, he was still awake when my fears came to visit and wouldn’t leave.
"I crawled out of bed, put my slippers on, and went down to talk with him. Maybe the tour wasn’t a very smart idea, I told him. Maybe the book will flop.
"Barack put his arms around me and placed his forehead on mine. 'It’s good, Miche,' he told me. 'It really is.'"
The couple left the White House in 2017, when Donald Trump and Melania Trump took over in Washington DC.
Last August, Obama – a former lawyer – revealed how she had been suffering from “low-grade depression” due to worries over the coronavirus pandemic, racial injustice and the Trump administration.
Speaking on her The Michelle Obama Podcast, she explained how she had been struggling with sleep and her exercise routine.
Obama said: "I’m waking up in the middle of the night because I’m worrying about something or there’s a heaviness.
“I try to make sure I get a workout in, although there have been periods throughout this quarantine where I just have felt too low.”
The best-selling author – whose daughters Malia and Sasha are 22 and 19 respectively – admitted she had been going through “those emotional highs and lows that I think everybody feels, where you just don't feel yourself”.
She added: "These are not – they are not fulfilling times, spiritually. I know that I am dealing with some form of low-grade depression.
“Not just because of the quarantine, but because of the racial strife, and just seeing this administration, watching the hypocrisy of it, day in and day out, is dispiriting.”