Sienna Miller: Little Sleep and Travel Chaos!

has said that she's surviving on 'very little sleep' as she opened up on returning to work just three weeks after giving birth while appearing on The Tonight Show With .

The British actress, 44, returned to business as usual with her glamorous chat show appearance just three weeks after welcoming the tot with boyfriend Oli Green, 29.

The couple are already parents to a two-year-old daughter, while Sienna is also mum to daughter Marlowe, 13, whom she shares with ex-fiancé . 

During her appearance on the show she opened up about the transition of having another child and spoke about her nightmare flight over to the US to promote new action movie Jack Ryan: Ghost War.

Sienna said: 'It feels like stringing sentences together is a bit challenging. I'm on very little sleep but I'm madly in love with my baby.

'It's crazy to be talking words and wearing a dress. What has happened from pajama gate.' 

Asked by the host which of her children are tougher to look after, she said: 'I would have said the teenage girl would be harder to juggle until the transatlantic flight I took yesterday with the toddler and the newborn. 

'The toddler now wins hands down. It was an absolute disaster. There's no negotiating.

'I got to the immigration line and just broke down.'

Sienna announced that she had welcomed her second child with Oli, telling E! News last week: 'It's happened. I have a tiny baby next door. It feels like stringing sentences together is a bit challenging...

'I'm on very little sleep but I'm madly in love with my baby.'

She is currently blazing the promo trail with her latest movie, Jack Ryan: Ghost War, and announced the sweet news to the publication in her promotional interview.  

Sienna announced her third pregnancy by revealing her blossoming bump at the star-studded  in December. 

It was only right for the actress to make her revelation with a statement look on the blue carpet outside the Royal Albert Hall in London. 

And it is not the first time Sienna has used the red carpet at a fashion event to announce she is .