Following on from Prince Harry's call for more people to open about their mental health. William and Gaga discussed the important of abandoning the stiff upper lip syndrome.
The pop star recently discussed her experiences of Post Traumatic Stress Disorder, after being raped when she was 19. In December 2016, she published an open letter about her battle with the illness in the hope of initiating a greater conversation about similar issues.
"I read the open letter you wrote the other day and thought it was very moving and very brave of you to write down such personal feelings," said William over Skype. "I wanted to ask you how you found speaking out and how it made you feel."
Gaga revealed that the prospect of the letter made her "very nervous at first", but that ultimately she felt it was important to try and remove the stigma attached to it.
"For me, every morning waking up sad and going on stage is very hard to describe," she explained. "There's a lot of shame attached to mental illness; you feel like something's wrong with you. In my life, I look at all the beautiful things that I have and think 'I should be so happy' but you can't help it if you wake up and feel so tired and so sad; you have anxiety and you can barely think. It was just saying this is part of me and that's ok."
"The little bits that I've learnt about mental health is that it's ok to have that conversation; it's really important to have that conversation and that you won't be judged," he said. "It's so important to break down that taboo otherwise it'll lead to problems further down the line."
William was instrumental in helping his younger brother, Harry, deal with his grief after their mother, Diana, Princess of Wales, died when they were young. The Duke encouraged his sibling to open up and eventually Harry sought counselling.
Prince William said in another interview for charity Calm (Campaign Against Living Miserably) that he and Catherine wanted to raise their own children to be open about their emotions.
"Catherine and I are clear that we want both George and Charlotte to grow up feeling able to talk about their emotions and feelings," he said.
"Emotional intelligence is key for us all to deal with the complexities of life and relationships."