The 88-year-old, who as a young adult developed a case of pleurisy and had part of one of his lungs removed, has been in Rome's Gemelli hospital since Friday for bronchitis treatment.
Francis, who has been pontiff since 2013, has had influenza and other health problems several times over the past two years.
The Pope spent a peaceful night in hospital and ate breakfast this morning, the Vatican said.
Pilgrims arriving at the Vatican this week have offered their prayers that the Pope would recover soon.
It comes after it cancelled the Pope's weekend engagements after he was diagnosed with bilateral pneumonia.
