The motorway was shut in both directions by the police between junction 28 and junction 27 shortly before 10am yesterday due to concern for a man’s safety.
The closure has led to significant congestion and long tailbacks covering several miles in both directions.
It was re-opened in the afternnon but it took hours for traffic to ease.
On its Twitter feed, Derbyshire Police said: “The M1 between J28 and J27 is now being re-opened in both directions, but it will take a while for the traffic to clear.
"Thank you to drivers for their patience.”
A Derbyshire Constabulary spokesman said around noon: “The incident was a concern for the safety of a man.
“The incident was resolved with nobody being hurt and the road is now reopened.
“Thanks to drivers for their patience.”