Heather Mills only sleeps for five hours a night.
The 47-year-old activist is thankful for her vegan diet because she thinks it gives her more energy and makes her more productive.
She said: "I found I had more energy [when I went vegan].
"I just love that feeling that I wake up in the morning and I don't feel sluggish or rough and I've just got consistent energy.
"It means that I've got more hours in the day because I'm awake for 18, 19 hours of the day and I get 20 times more done.
"I just want to try and make a difference while I'm here and create a healthy legacy for my children and my friends' kids in the future to come to be honest."
And Heather - who has a 12-year-old daughter, Beatrice, with ex-husband Sir Paul McCartney - uses the extra hours in her day to hone her linguistic skills.
Asked what she does in the early hours of the morning, she said: "All the endless emails and learning German which is a bloomin' hard language.
"Take Slovenian, Italian and French they're all easy, German is a nightmare with all the 'die', 'das', 'dere'. Four words for the word 'the', it's just insane. "