His comments come after rumours continue to circulate of infighting between cardinals at the Vatican over the meaning of the pope's apostolic letter on marriage - Amoris Laetitia.
Since the letter's release last year, some leading Catholics have argued that the Pope has not been clear enough in the teaching about whether or not divorced Catholics should be allowed to take communion.
"There is corruption at the Vatican but I am at peace," the Pope told Corriere della Sera.
When asked about how he deals with stress, the Pope joked: "I'm not on tranquillisers."
The pontiff added that his secret to a good night's sleep was writing down all his problems in a letter to St Joseph.
Pope Francis leaves his worries at the feet of a statue of St Joseph
He said that after writing the letters he places them at the feet of a statue of the carpenter.
"And now he is sleeping on a mattress of letters! That's why I sleep well: it is the grace of God. I always sleep six hours. And I pray," the pontiff explained.
The Catholic leader said that when he was younger he was a lot more anxious about life but said things changed for him when he was elected Pope in 2013.