Born in Mosterhamn, a small settlement on the Norwegian island of Bømlo, Sivertsen made a musical debut playing the bass guitar at a Christmas party at age 8.

Sivertsen worked with a number of prominent American jazz musicians, including Michael Brecker, Mike Mainieri, Tony Levin, and Bob Mintzer.

The albums Remembering North (1993) and One Day In October (1998) were both released in the United States, and were received to favorable international acclaim.

The damage from the fall caused a brain haemorrhage which forced doctors to remove parts of his skull for him to be able to survive the ordeal, and he spent nearly a week in a coma following surgery.

Sivertsen died on Haukeland Universitetssykehus in Bergen on Christmas Eve 2006 from complications from epilepsy and the several brain haemorrhages suffered the previous two years.