Players start to regenerate lost health after going 5 seconds without taking damage, similar to Halo or Guild Wars health regeneration. The amount you regain each seconds increases every 5 seconds to a max of 5 per second.

There is one config var:

#Our one config var, determines how 'healing is displayed 1 = Menu, 2 = Hudhint, 0 = Off message_type = 2

~J3ff