Hyper vigilance is a sign of a problem sometimes it is associated with PTSD or Paranoid schizophrenia. Either way a doctors care is required for this..
I would have associated hyper vigilance with paranoia rather than depression.bi polar disorders are more associated with mood swings and personality disorders would be more associated with anti social behaviours. It sounds like a form of paranoid schizophrenia. Ask your doctor for a psychiatric referral if its a family member.
Hyper vigilance is also an distinct symptom of Reactive Attachment Disorder (RAD). Childhood and in uetro trauma can cause RAD. My step-son is extremely hyper-vigilant and after diagnosis of bi-polar, depression, PSTD, we found the root cause as an Attachment Disorder and he has made huge progress.