Jim Parsons doesn't get up later than 6am on his days off.

The 'Big Bang Theory' star never sleeps in even when he doesn't have to be anywhere in the mornings because he loves to get up early and start exercising after chowing down on a healthy breakfast, and he then helps himself to another portion of morning food to keep him going.

When asked what he does on a day he's not working, he said: ''I still get up very early - the latest I would get up on a day like that is probably 6am.

''I will have two cups of coffee, a protein shake and bowl of oatmeal. Then I'll go on the treadmill for five miles, I'll probably do some sort of abs exercise, sit ups or something and then I will come in and have more breakfast, probably eggs, and then I'll take a shower and ... then it's hard to say.

''I may watch the news or read because it's a day I'm not working ... then I start thinking what's going to be for dinner and I start getting excited for bed again.''

But the 41-year-old star - who plays Sheldon in 'The Big Bang Theory' - insists his life nowadays is quite different to how he was as a child and admits he isn't sure why he was such a fan of US sitcom 'Mork & Mindy', which starred the late Robin Williams as extraterrestrial Mork, during his younger years.

He added to Metro newspaper: ''I recently remembered I had a 'Mork & Mindy' birthday party and I loved the show 'Mork & Mindy'. And as much of an admirer of Robin Williams as I've always been, I can watch a re-run of 'Mork & Mindy' now and think, 'I was five of six years old, what was the appeal to me?

''Who was that kid?' I don't know!''