The former British prime minister, David Cameron, has said he has been "hugely depressed" by the outcome of the Brexit vote.
He told The UK Times he is "truly sorry" for the political turmoil it has unleashed, admitting his approach "failed".
Mr. Cameron has also accused the current Prime Minister, Boris Johnson, and Conservative, MP Michael Gove, of behaving "appallingly" during the referendum campaign.
David Cameron gave the green light for the vote to take place in 2016.
Both Mr. Johnson and Mr. Gove were prominent figureheads for the 'Leave' campaign.
"Over the issue of whether or not we had a veto over Turkey [accession to the EU] and over the issue of the £350m on the bus, I think they left the truth at home," Mr Cameron said.
He also criticised Mr. Johnson's recent behaviour in suspending the British parliament for five weeks - a move many critics say is a tactic to stop MPs interfering with his Brexit strategy.
Mr. Cameron said: "Taking the whip from hard-working Conservative MPs and sharp practices using prorogation of parliament have rebounded.
Mr. Cameron was asked whether he has trouble sleeping: "I worry about it a lot. I worry about it a lot," he replied.
He also revealed that the morning after losing the EU referendum he phoned Barack Obama and European leaders to tell them he was "sorry" for the outcome.