NSW Premier Mike Baird breaks his back in late night fall down the stairs

New South Wales premier Mike Baird has broken his back during a late night fall down the stairs.

Mr Baird published an X-ray image on his Facebook page on Tuesday morning, showing a cracked vertebrae that he blamed on a late night trip down the stairs to get a glass of water.

"Note to self: when fetching a glass of water late at night, don’t walk down the stairs in your socks with the lights out," Mr Baird wrote.

However, he was upbeat despite the official diagnosis confirming a fractured vertebrae.

"Prognosis: slowish recovery but no need for surgery," he wrote.

"Yeah, I know… The punchlines for this pretty much write themselves… Knock yourselves out (I almost did!)"