Mindfulness training is getting increasingly popular – it can be offered in workplaces, schools, and even on TikTok.
But while the technique is aimed at relieving stress and depression, it can sometimes make mental health problems worse.
Now research suggests that the practice can also trigger strange mental experiences, such as making people feel disconnected from their body. “In order to make an informed decision, people have to know what things can happen,” said Dr Julieta Galante at the University of Cambridge, who did the research. “The priority is to make people aware.”
For those who haven’t tried it, mindfulness is simple form of meditation, involving focusing on thoughts, feelings and external sensations – like the sound of a clock.
The idea is that it helps people stop ruminating on things that are making them unhappy or stressed. And studies have shown that it can help people feel less depressed and anxious. According to NHS guidelines it is as effective as taking antidepressants or having psychotherapy.
But the approach is increasingly being offered to people without these conditions, as a stress reliever or relaxation technique.
In the latest trial, Dr Galante investigated the effects of an eight-week course in mindfulness in university students. They were randomly assigned to either get the training or just have usual mental health support, if needed.
As expected, those who did the the course got less distressed by their end-of-year exams. But they were also more likely to report some unusual experiences, including what are known as altered states of consciouness.
Some of these were pleasant, including spiritual experiences or a sense of bliss. But other sensations included feelings of “disembodiment”, which could be strange or frightening.
“You start feeling the limits of your body are a little less clear, where your body ends and where space begins,” said Dr Galante, who has had such feelings while meditating herself. “A stronger experience may be that your body feels bigger than it is, maybe that your body gets to the walls of the room.”
In other surveys of mindfulness practitioners, people have reported feeling as if they are not present, that they are watching themselves or as if they have left their body.
Such experiences can also happen in everyday life, for instance, during deep emotions, such as sadness, love or spirituality, said Dr Galante.
But in her study, students who got the mindfulness training were more likely to have the disembodiment feelings than those in the comparison group, with rates of 42 and 26 per cent respectively, a year later.
And in those who had done the course, sometimes the weird sensations popped up unexpectedly. “Although most of the experiences happen during the mindfulness practice, it is not unusual for them to occur outside of it as well,” said Dr Galante.
The findings make sense, as modern mindfulness techniques stem from older Buddhist meditation practices that aim to make people feel at one with the universe.
“The disembodiment experience would be an indication that you have an insight into the nature of reality, because, for Buddhists, the nature of reality involves having no self,” Dr Galante said.
Willem Kuyken, at the Oxford Mindfulness Centre, who was not involved in the study, said there was good evidence that mindfulness helps reduce depression and anxiety. “Mindfulness meditations are potentially quite a powerful way of training the mind,” he said. “With anything that’s effective, there may be side effects.”
But the latest study is not the first to identify potential harms from mindfulness or meditation. Other concerns include that in some people, it makes them feel more anxious or distressed.
It is hard to know how common such events are, but in one recent US survey they affected about one in 10 had any such negative experience lasting for more than a month afterwards.
“There needs to be a public acknowledgement that mindfulness usually leads people into altered states of consciousness and and these may be pleasant, or these may be unpleasant,” said meditation expert Miguel Farias at Coventry University.
“The problem now is that the industry is massive, and there is no warning that some people may experience something unpleasant as a result,” he said.
“There has to be a public knowledge that it’s not just like relaxing in the bathtub. This does more than that for many people.”
What is mindfulness?
Mindfulness is a simple form of meditation that is designed to reduce symptoms of anxiety and depression.
The technique involves taking some time to sit silently and pay attention to internal or external sensations. It can help to breathe slowly and deeply, while you start noticing, for instance, the feeling of clothes against your skin or the sound of a ticking clock.
If people experience troubling thoughts, they should try to just notice their presence, rather than letting them take over.
People can practice mindfulness for just a few minutes a day, or may have longer sessions. Some recommend becoming more mindful as part of daily life, for instance, trailing our hand along a banister as we walk upstairs to notice how it feels against our skin.
People used to mainly learn mindfulness through courses provided by teachers, but there are now many apps or online courses where people can teach themselves.