Brighton and Hove City Council mental health staff are holding a 32-day strike over working patterns imposed by bosses.
The Approved Mental Health Professionals began their walkout on 31 October.
They are striking between 10pm and 8am.
They had agreed to work 8am-2pm and 2pm-10pm shifts with a voluntary standby rota to cover nights.
But bosses imposed new working patterns on 1 November that could see staff forced to work consecutive night and day shifts.
Workers argue this could put both staff and service users at risk.
The Unison union members previously struck over the attack in September.
Brighton and Hove Unison says senior officers in Adult Social Care sent a letter to workers threatening suspension or dismissal if they struck again.
A Unison meeting last month voted unanimously to ballot the whole of its council membership for action against the threats.