Can frenemies harm your health? Team say HALF our acquaintances fall into category Researchers say half ourÂ acquaintancesÂ are people we both love and hate Tracked blood pressureÂ duringÂ interactions with people Frenemies cause blood pressure to spike - even if they are just in the same room, or if their name was mentioned We may have more frenemies - people we both love and hate - than we realise, and they may be harming our health, researchers have warned. Experts say on average about half of our social network consists of people we have, as they put it, an 'ambivalent relationship' with.Â They say the stress of these relationships is harming our health. Rachel McAdams (left) pictured as Karen Smith, with Lindsay Lohan as Cady Heron, in Mean Girls. Researchers now say that frenemies can actually harm your health. Individuals were given a blood pressure monitor and told to take a recording whenever they interacted with someone.Â During interactions with frenemies, people's blood pressure spiked, indicated an increased level of stress.Â When the frenemy was in the other room, representing the potential for awkward conversation, researchers measured the same rise in stress levels. 'It is rare to encounter someone who doesn't have at least one ambivalent relationship,' Julianne Holt-Lunstad at Brigham Young University in Utah, told the BBC.Â They found, as expected, highly 'aversive' persons such as an unreasonable boss raised blood pressure more than the 'supportive' group.Â However, blood pressure actually rose the most for the ambivalent ties, such as an overbearing parent.Â Further research by Holt-Lunstad showed that blood pressure rose even when the participants were merely exposed to subliminal triggers that reminded them of the 'ambivalent' social contact, like flashing the person's name on a screen. 'Even when the other person is just in another room in the lab, they have higher blood pressure and higher levels of anxiety,' Holt-Lunstad told the BBC.Â 'It's just the anticipation of having to interact with them.' Previously a Danish study also found worries, conflicts and demands in relationships with friends, family and neighbors may contribute to an earlier death. Men and people without jobs seemed to be the most vulnerable, Rikke Lund, a public health researcher at the University of Copenhagen, and her colleagues found. 'Conflicts, especially, were associated with higher mortality risk regardless of whom was the source of the conflict,' the authors write. Worries and demands were only associated with mortality risk if they were related to partner or children. Friends or frenemies?Â Experts say on average about half of our social network consists of people we have, as they put it, an 'ambivalent relationship' with. The health-protecting effects of support from a social network and close connections with family and friends are widely recognized, Lund's team writes in the Journal of Epidemiology and Community Health. 'Less is known about the health consequences of stressful aspects of social relations, such as conflicts, worries and demands,' they write.Â Â Holt-Lunstad doesn't want people to get the impression from this study that ending all imperfect relationships is the right thing to do. 'Not all relationships are equal - we need to be careful about the negative aspects as well,' she said.Â 'We know that social isolation is bad for us as well,' she said.Â 'They're probably both bad and that's why it might be important to foster the positive aspects rather than just focusing on cutting people out of your life.'