William raised the subject at the OBE ceremony at Buckingham Palace on Tuesday. He presented the cyclist Geraint Thomas with his OBE, before asking the sportsman how life was with a three-year-old son. Mr Thomas told reporters afterwards that William asked “how the sleepless nights were going”.
He added: ”He said their first one took a while for his sleep to kick in.
“You don't really know what to expect, but to chat to him about the rugby and my baby was surreal."
Others at the prestigious ceremony included the photographer Terence O'Neill.
Mr O’Neill has photographed a wide variety of famous people, from Winston Churchill to Nelson Mandela to the King of Rock and Roll, Elvis.
He praised Kate for her skills as a photographer.
He said: "She's a very good photographer. She will keep it in the family."
Talking about his own photographs, Mr O’Neill added: "There have been some incredible people.
“I couldn't really even compare – his (the Duke of Cambridge's) wife is also an excellent subject."
The Duke and Duchess have spoken many times before about the sleepless nights they suffered while bringing up their three children.
However this was the first time William singled out George.
After George’s birth, William told reporters at the Anglesey Show in North Wales that:"The new addition, he's doing all right.
“I’m getting my head down during the day. He is lovely. There have been a few sleepless nights but he's sleeping much better now."
Cute little George used to wake up six times a night, keeping not only his parents awake, but also Kate’s parents.
To help George get to sleep, the Duke used to sing him Coldplay songs.
William belted out his favourite hits Yellow and Paradise to calm the crying prince back to sleep.
At the time, a royal insider said: “He's using a bizarre tactic of belting out Coldplay anthems at all hours of the night even though he can barely hold a note.
"It's even keeping Kate's parents awake.
“His favourite song is Paradise and he also loves doing Yellow.
“Coldplay aren't even his favourite band, but George responds to their songs the most and settles back down."
The source then added:"Wills is shattered by the morning so he heads to bed for a couple of hours and Kate springs back into action along with her parents."
The Duke and Duchess have just completed a very successful tour of Pakistan.