Tyra Banks ''stayed up all night'' to develop the concept of smizing.

The 46-year-old model has become synonymous with the term - which means to smile with your eyes - and she's now explained how she developed the idea.

Tyra said: ''I came up with it because there's a way that when you look at a photo and you feel nothing, it's actually because the person is not smizing. So it's like their eyes are dead, and they're not giving you anything.

''So for me, I turned that into smiling with your eyes. And I would teach models and even my family and friends about smiling with their eyes. And I was like, wait, that is too much.

''When we tell somebody to smile for the camera, we say cheese. So I need to make this one syllable. So I stayed up all night, y'all.

''One night, I stayed up all night. And I was writing on my paper smeyes (ph) - S-M-E-Y-E-S, smeyes, S-M-I-S-E, smilize (ph), all this stuff.''

Tyra was also quick to recognise the potential commercial value of the expression.

Speaking to NPR, she explained: ''Finally, I was - I put S-M-I-Z-E. And I was like, that's it. And then I ran and trademarked it before I said it anywhere in the world.''

The world-famous model also acknowledged there are various ways to smize.

Tyra - who is set to host the new series of 'Dancing with the Stars' - shared: ''There's many different ways. There's a sultry, sensuous, fierce smize. And you need to be thinking about something that you love, like pizza.

''Then there's the smize of delight and of pleasure and of sweetness. So there's, like, different ones. And you have to think of different things to create a different - to activate a different muscle in your face.''