Glen Bollands, 46, was last seen at about 4am today (Thursday) at his home in the city.
However, officers from North Yorkshire Police are now concerned for his welfare.
They have appealed for anyone who knows his whereabouts to get in touch.
Mr Bollands is described as being white, 6ft tall, with short brown hair, blue eyes and a thin build.
It is believed he is wearing a black coat, a green Nike jumper, jeans, and trainers with a dark orange trim.
Anyone with information is asked to call police on 101, quoting reference number 12180208865.