Bernard-Henri Lévy is running on fumes. Plus ça change. “I slept as always last night, a few hours, with chemistry compelling me to sleep,” the Parisian public intellectual tells me when we speak on the phone. “I miss the process of sleep, the process of getting awake, all parts of the ceremony I miss. But insomnia has given me more than it has taken. More time, certainly more work, more vigilance; I’m awake.”

His latest book, Nuit Blanche, which has yet to be translated into English, is a runaway bestseller in France, where it was released in January. It is an ode to insomnia, a meditation and a reflection upon the experience and the meaning of sleeplessness, from which the 76-year-old has suffered for decades.

Written with the intimate tone of a confidant, it takes the reader from his extensive library, which he organises and reorganises during dark hours of wakefulness, to his bedroom, where we encounter his wife and the “pharmacie de nuit” that allows him to snatch at least four hours of medicated unconsciousness. And it takes us, of course, to war zones.

The journey into geopolitics begins in the garret, where we are permitted to peer through Lévy’s window onto the world; his apartment is opposite the Palais de l’Élysée and sometimes, while sitting awake, he sees the president’s light come on in the small hours.

“When I see Emmanuel Macron has arrived at home, I send him a message and sometimes we have a deep discussion,” he tells me. “He plays an interesting role in Europe these days. While we are speaking he holds the flame of the free world’s values regarding Ukraine and Russia with calmness, wisdom and bravery. So he behaves well.”

The two men have been close for years but do not always see eye-to-eye. “I did not agree with him on Israel at all after October 7,” Lévy points out. “The IDF cannot withdraw from Gaza with Hamas still standing. I told him so both publicly and privately. But I must say, today in the general war of civilisation between democracy and autocracy, he does the job with honour.”

“At the London summit two weeks ago, honestly, God knows I’m not chauvinistic, but if you compare the speeches of your Prime Minister and Macron, Macron was much truer with his words and braver and more correct than Keir Starmer, who reduced the importance of the moment. Starmer did not find the words. He lacks a sense of history. I feel Macron understands the burning importance of the moment. I don’t think Starmer does.”

Fighting talk for a man about to land in Britain. On Tuesday, under the auspices of the Hexagon Society – a cultural institute aiming to connect France and Britain to strengthen liberal democratic values and fight progressive radicalism – Lévy will be appearing in central London in conversation with the distinguished historian Simon Sebag Montefiore. (A fellow insomniac, as it happens. A mark of intelligence? Conscience? Personally, I suffer the opposite. Sebag tells me: “I do worry about the world at night. Since October 7, it has been terrible. But I also worry about books and how to write them. Writing a book is like having a love affair, you’re either heartbroken or you’re infatuated. You can’t sleep either way.”)

So what does this surreal global moment demand? This is the question of our times. Clouding the minds of Lévy and Macron, as it clouds the minds of us all, is the orange shadow of the most powerful man in the world. In the dying days of last month, when Volodymyr Zelensky was humiliated in the Oval Office, Lévy was in a dank cellar on the front lines in Ukraine alongside members of the National Guard. It was his seventeenth visit since the war began.

“The Ukrainians felt less harassed by it than we did,” he says. “There is fatigue of opinion in the West which I don’t find to the same degree, paradoxically, in Ukraine. They hold firm, they stand by their values, they fight still very bravely.

“When this disgusting humiliation of Zelensky happened, I saw at the same time their sorrow but also their real pride at how stiff and firm was their president. He gave them energy to move on, to proceed and continue to defend themselves. Far from discouraging them, my feeling is that it only exalted them, called them for more resistance.”

But this is the stuff of poetry. In the real world, Ukraine will almost certainly be forced to cede territory and be unmanned further by an American minerals deal. “I hope there will not be such a humiliation,” Lévy responds defiantly. “But if so, it will be our dishonour, not theirs. They will have fought to the last minute, shed their blood. It would be the weakness and cowardliness of the West which will be exposed to the world. Most of all, I mean America.

“I say that with deep sadness because I love America. I would not be born a free man without American GIs and brave British pilots and fighters on the ground. But I must say, the America of Trump made an absurd, suicidal and terrible choice when he chose Putin. Even Fox News are shocked. They defended Trump but they are shocked by this moment, this U-turn of American policy. They are shocked by the way he treated Zelensky, a man who believes in the American creed.

“That is their dishonour but we, Europe, did not do enough. The fact that there is an invader and an invaded, and that we are the final targets of the invasion, was obvious from the beginning. We were too timid.”

Zelensky – whom Lévy has known since before he was elected president – was so enamoured with the United States and its pre-Trump values that he did not see the betrayal coming. When the two men met in Paris at the reopening of Notre Dame in December, the Ukrainian leader still hoped for The Donald’s support.

“With all the respect and admiration which I have for Zelensky, I tried to say that it was really not clear to say the least,” Lévy recalls. “Trump showed all the signs for years of his proximity to Russia. He does not understand, or want to understand, that it is the same battle in Gaza and Ukraine. This is the same fight, shoulder-to-shoulder, back to back, with swords drawn, for Ukrainians and Israelis. Trump does not get the point. His entourage does not get the point. This is such a shame and such a pity for America.”

Other aspects of Trump’s foreign policy also keep Lévy up at night. The Frenchman is hawkish on Iran, sharing former Israeli prime minister Naftali Bennett’s view of the regime as “the head of the octopus” that threatens the stability both of the Middle East and further afield. He has long feared that Trump 2.0 may try to cut a deal with the Ayatollah. Sure enough, earlier this month the president disclosed that he had written to Tehran to offer talks.

“Trump could conclude a deal with Iran that might be worse than the Obama deal,” Lévy says. “I deeply hope with all my heart that I am wrong. If he does that, it means that he does not care about the brave women in Iran, the human rights defenders that long for a regime change, and he does not care as much as Israelis hoped about the security of Israel.”

Where is all this heading? Another sleepless question. “I fear to express this in words, as what I’m going to say makes me shiver,” Lévy ventures. “But one hypothesis is conceivable. We may be about to see the art of the deal applied to all the worst, anti-Western leaders in the world. Putin today; Khamenei tomorrow; the day after, Turkey; and one day, what would prevent such an administration making a deal with the Chinese and opening the gates for invasion of Taiwan? It would mean disaster for the West, for all the values of continental Europe.”

It seems to me that the replacement of a values-based foreign policy doctrine with an interests-based approach – which views a deal with Russia as no different from a deal with Canada – degrades the importance of democracy in the long term. Will Trump, who has never conceded the 2020 election, attempt to alter the constitution to secure a third term? When the time comes, will he ring Pavlov’s bell for his heavily-armed followers?

“So many inconceivable things happening in a few weeks that everything is conceivable, even what you are saying,” Lévy replies. “If American society doesn’t wake up, if true old Republicans don’t recover their spirits and their minds, if state governors don’t wake up, we could see the end of democracy. But my prediction is that you will have more and more Republicans who might be like sleepwalkers waking up suddenly, thinking: what are we doing with the heritage of George Washington and Ronald Reagan? I’m sure of that. I feel that.”

British Conservatives may be able to play their part in saving America from itself, he adds. “They have an influence in that game. They speak the same language and have brotherly links with the States even more than continental Europe. They have a big role to play in the awakening of the GOP.”

Well, what of Europe? As the White House withdraws its military might from the continent, the 27 members of the European Union plus Britain find themselves under-militarised and burdened by soaring taxes, trade deficits, huge welfare expenditures, sluggish economies, deep immigration challenges and hollowed-out national identities. We have been caught, as it were, with our pants down.

“What is really necessary is the will, the determination, the courage,” Lévy says. “Do we have it? I don’t know. Certainly not all of the 27+1 have it. But the coalition of the willing may have it, we will see. If we don’t have it, we have to find it. If not, we will be crushed and become a bridge between Trump and Putin. We have the prosperity, we have the chance to rebuild our war industry. We are the richest continent in all ways, in terms of our values, our money and our spirit, still today. If we combine it all to face the challenge, we can do it.”

Antisemitism is one symptom of the cultural malaise that threatens such solidarity. This is another problem that keeps Lévy’s eyes open in the dark. In Britain, it is now considered an opinion, he suggests; perhaps a bad opinion, but one that should be permitted in conversation. “It was not the case ten or 20 years ago,” he says. “Recently, I received an invitation from a British society to debate a man who represented Hamas. They said they would be happy if I could express the opposite point of view. I’m sorry, but that’s not a point of view.”

All of which leaves Lévy suffering the dark night of the soul. “The night is French,” he announces. “There is a whole French tendency in poetry and philosophy to praise insomnia. Baudelaire understood this, Mallarmé understood this. Emmanuel Levinas thought that insomnia was a duty because you have to care about your fellows and what is coming next.

“Maybe France invented during the Dreyfus affair this strange character of the public intellectual. Maybe it is somebody who considers himself a sort of sentinel and a sentinel does not sleep. It may be vain but it is embedded in French culture. Maybe I would sleep better if I was British.”

Bernard-Henri Lévy will be discussing Nuit Blanche in conversation with Simon Sebag Montefiore in Central London on 18 March. Tickets are available here