Hypervigilant: Very aware/tense/easily startled state

Hypervigilance is an anxious/expectant state. People who are hypervigilant (tense/nervous/awaiting danger/expecting attack) are that way for a reason.

Typically hypervigilance is present in an individual because of past trauma, like Vietnam vets and abused people for example.

A lot of times, hypervigilant people have rigid postures and taught muscles from being tense all the time.

Constant anxiety and watching of one's surroundings is tiring.