Boundaries are the limits or rules we each establish to protect ourselves. We should not be venting all our feelings to all people — promiscuous honesty, telling everyone everything, doesn’t help any of us. Recognising that boundaries enable us to take different versions of ourselves to different environments, like work, friends and family, is important for all of our mental health. When we indiscriminately express unfiltered feelings, we can disturb those around us, and not receive the empathic response we need. Human beings are wired to look for danger, and emotions are contagious. Our threat system can be pinged by the other, putting our brain into “code red” — fight, flight, freeze — heightening our sense of anxiety and conflict. When we are in a heightened state our capacity to think deeply and respond sensitively goes offline. It is an evolutionary survival mechanism and the source of most aggression.