JOIN USIn fact, the study, led by led by Sydney's University of Technology, has found that some couples are so in tune that their brains begin to work in synchronisation -- with parts of their nervous systems beating in harmony.
The scientists studied the brains and heartbeats of 30 volunteers during counselling sessions by counsellors and found identical patterns of brain activity in those who had become so close they were "physiologically aligned".
That means they had reached a state in which their nervous systems were ticking over in harmony, helping them to know each other's thoughts and emotions, the 'Daily Mail' newspaper reported.
The scientists believe the findings also shed light on the behaviour of couples, close friends or family members.
Psychologists have long known that some couples learn to think like each other -- allowing them to "know" what their partner is thinking or about to say. But, this new study goes further by looking into the activity of the nervous system.
In fact, Dr Trisha Stratford, who led the study, identified a crucial moment when the counsellor and patient's brains started to work in sync in an "altered state".
She said: "When this happens we can read each other's brains and bodies at a deeper level -- a sixth sense." During the "altered state", the part of each person's brain that controls the nervous system began to beat together.