“…Rapid eye movement (REM) sleep and its main oscillatory feature, frontal theta, play a critical role in the processing of recent and emotional memories (for reviews, see Walker, 2009 ; Walker and van der Helm, 2009 ; Genzel et al , 2015 ; Hutchison and Rathore, 2015 ). Although recent studies indicate that slow wave sleep (SWS) could play a complementary role in this processing ( Cairney et al , 2015 ; Payne et al , 2015 ), compelling evidence supports the offline benefit of REM sleep for the processing of emotional memories ( Wagner et al , 2001 ; Lara-Carrasco et al , 2009 ; Gujar et al , 2011 ; van der Helm et al , 2011 ; Baran et al , 2012 ; Payne et al , 2012 ; Groch et al , 2013 , 2015 ; Spoormaker et al , 2014 ), and suggests frontal theta activity as a brain mechanism underlying such processing ( Nishida et al , 2009 ; Prehn-Kristensen et al , 2013 ; Cowdin et al , 2014 ; Durrant et al , 2015 ; Seeley et al , 2016 ; Marquis et al , 2017 ).…”