Does Depression Prevent Suicide?
Soper’s hypothesis – which I’ve been interested in since he first wrote about it in 2014 – is that many mental illnesses (such as depression and anxiety) are evolved defenses against the special risk that human cognition presents: the ability to conceptualize ending all of one’s problems by ending one’s brain.
.. Soper includes delusional disorders in his hypothesis; indeed, self-delusion appears to be a way of avoiding the horrors of reality and the mortality risk that they may present. But since the etiology of e.g. schizophrenia seems to be novel mutations, these disorders are probably terrible accidents, rather than protective adaptations. I will focus on depression here.
.. Depression is a kind of paralysis. Excessive sleeping is common (though inadequate sleeping may also be present). Whether sleeping is affected or not, many depressed people are unable to leave their beds or homes very much. They cannot form coherent plans and act on them.