Mid 17th century; earliest use found in Henry More (1614–1687), philosopher, poet, and theologian. From post-classical Latin psychopannychia from ancient Greek ψυχο- + παννύχιος lasting all night from παν- + νύχιος belonging to night, taking place at night from νυχ-, alternative stem of νυκτ-, νύξ night, cognate with night + -ιος, suffix forming adjectives. With the some forms compare -y, and also Middle French psychopannychie.