Hayden was born in Waterford in 1959, but is a native of County Carlow. She moved to Dublin and attended St Joseph of Cluny Secondary School. Hayden did a Bachelors of Economics and History in University College Dublin (1981). She also obtained a PhD in Applied Social Sciences.[2][3]
Hayden qualified as a solicitor and practiced between 1989 and 2008.[2]
She became Chair of Threshold in 1999. She was also a Board Member of the Private Residential Tenancies Board from 2004 to 2011. She resigned her Board membership when she was appointed to the Seanad.
Hayden received a PhD in Housing Policy from University College Dublin in 2014.