The number of people being taken into custody has dropped since the launch of a new scheme in Eastbourne which sees mental health nurses out on patrol with police officers.
Watchdogs say fewer people are being taken into custody since nurses started going out on patrol and sitting in the police control room.
It is part of a street triage scheme to improve how those with mental health issues are treated in emergencies.
Police force figures show a 44 per cent fall in people detained in custody for their safety since it began last October.
The year-long pilot schemes are funded by the Department of Health and backed by the Home Office.
They were launched after a joint investigation by Her Majesty’s Inspectorates of Constabulary and Prisons, the Care Quality Commission and the Healthcare Inspectorate Wales, which called for a rethink of how powers were used to detain people in a “place of safety”.
Sussex Police was found to have a higher number of people with mental health issues taken into custody compared with other forces in the south east.
In the past, police would use a Section 136 order to detain people for their own safety although they had not committed a crime.
Since the launch of the pilot, Sussex Police said it was called to 180 cases with 155 people assessed.
Of those where previously Section 136 orders would have been used, 63 have been avoided, the force said.
In a four-month period before the pilot, between October 2012 and January 2013, 77 people were taken into custody, with a further 27 taken to a hospital suite.
In the same four-month period after the trial began, 43 people were taken into custody and 35 to Eastbourne District General Hospital.
The pilot project runs until October 2014.