The pain-relieving effects of nitrous oxide – laughing gas – may be enhanced by suggestion or hypnosis, according to a new study by UCL (University College London). The study’s findings – that people are more suggestible under the gas – mean that dental patients may benefit from being coached to relax while undergoing sedation.
Nitrous oxide (laughing gas) is commonly used by dentists to sedate their patients before treatment, but some dentists believe their patients also become more suggestible while under the influence of the gas. A number of dentists have been trained in hypnosis and find that their patients respond well to being spoken to in a quiet, hypnotic manner – the new findings suggest that these effects could be further enhanced with laughing gas.
The UCL study set out to establish whether laughing gas does indeed boost imaginative suggestibility – a trait closely related to hypnotic suggestibility – and imagery vividness. Thirty participants took part in two sessions where they were given a mask from which they breathed in air or 25 per cent nitrous oxide. The volunteers were not told which type of gas they were being given, and the mask was scented to disguise the sweet smell of the laughing gas.
During each session, participants were given a series of mental imagery tests and were asked to rate their response according to a scale of 1-7, where 1 was ‘as clear and vivid as the real thing’ and 7 was ‘no image present at all’. For example, participants were asked to close their eyes and imagine tasting oranges or smelling roast beef, feeling linen or hearing the honk of a car horn.
Volunteers were also put through a series of ‘imaginative suggestibility’ tests based on suggestions given to them while under the gas. The suggestions were worded to invite the participant to experience hallucinated sensations. For example, they were told to imagine a sour taste in their mouth, and were told that after a while they would actually begin to experience a sour taste in their mouth, and that this would become stronger and stronger. Or they were told that a voice would come out of a (non-existent) speaker in the corner of the room, and that the voice would ask them a number of simple questions about themselves. If the participant responded well to the suggestion, he/she would answer some of the questions that the hallucinated voice had asked.
The study, published online in the journal Psychopharmacology, found that the nitrous oxide boosted imaginative suggestibility by approximately 10 per cent. This effect was unrelated to participants’ expectations regarding the effects of the drug.
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