Existential anxiety:

Theologians like Paul Tillich and psychologists like Sigmund Freud have characterized anxiety as the reaction to what Tillich called, "The trauma of nonbeing." That is, the human comes to realize that there is a point at which he or she might cease to be (die), and their encounter with reality becomes characterized by anxiety. Religion, according to both Tillich and Freud, then becomes a carefully crafted coping mechanism in response to this anxiety since they redefine death as the end of only the corporal part of human personal existence, assuming an immortal soul. What then becomes of this soul and through what criteria is the cardinal difference of various religious faiths.

Philosophical ruminations are a part of this condition, and this is part of obsessive-compulsive disorder. They are typically about sex and religion or death.

According to Viktor Frankl, author of Man's Search for Meaning, when faced with extreme mortal dangers the very basic of all human wishes is to find a meaning of life to combat this "trauma of nonbeing" as death is near and to succumb to it (even by suicide) seems like a way out.