New research suggests that dairy products, cheese in particular, could give people nightmares. Research published in the journal "Frontiers in Psychology" found that people with a severe lactose intolerance were more prone to bad dreams and insomnia. Professor Marie-Pierre St-Onge, director of the Dream and Nightmare Lab in Montreal, Canada, analyzed the diet, health and sleep patterns of more than 1,000 people. She wanted to investigate the degree to which food affected dreams. She based her research on a 2015 study that looked into "food-dependent dreaming". Participants in the 2015 study blamed cheese and other dairy products for disturbing their sleep.

Dr St-Onge discovered that people with gastrointestinal problems and lactose intolerance had scarier and more frequent nightmares. She said: "If you have gastrointestinal issues, that could account for a lot of what's happening in terms of sleep disturbances that could be associated with different dreams." Her colleague, Dr Tore Nielsen, said: "Sleep disturbances affect a huge proportion of the general population. One large survey found that 30-40 per cent of individuals will have a clinically significant sleep disorder in their lifetime." Previous research suggests that about 85 per cent of adults have a nightmare at least once a year, with about 5 per cent of people experiencing them frequently.