Can Cheese and Yogurt Cause Nightmares? New Study Links Dairy and Disturbed Dreams to Lactose Intolerance
A Canadian study finds a potential connection between nightmares and dairy consumption—especially in people with lactose intolerance—raising questions about how gut discomfort influences dream quality.
Watan-Could the cheese or yogurt someone eats at night be the source of their nightmares? It’s a serious question now, following a new Canadian study that found a possible connection between disturbing dreams and lactose intolerance—likely due to the digestive symptoms these foods cause.
For a long time, popular wisdom has held that a light dinner improves sleep, but few scientific studies have explored the impact of diet on dreams. Now, researchers publishing in Frontiers in Psychology have surveyed 1,082 students at MacEwan University over four months to understand their eating habits, sleep quality, and specifically their nightmares—and found a potential link.
About 40% of participants felt their diet affected sleep quality, with 24.7% reporting a negative impact and 5.5% stating their dreams were affected. Participants cited sweets (22.7%) and dairy (15.7%) as the most sleep-disruptive foods. These were also associated with “weird” or “disturbing” dreams in 29.8% and 20.6% of respondents, respectively.
In contrast, foods like fruit (17.6%), vegetables (11.8%), and herbal tea (13.4%) were reported to improve sleep.
The Lactose-Nightmare Link
Dr. Tore Nielsen, a neuropsychologist at the University of Montreal and lead author of the study, explained that many people with lactose intolerance still consume dairy products. The severity of symptoms depends on how much lactase enzyme their small intestine produces.
This leads to subtle bodily discomfort during sleep—such as bloating or cramps—which may unconsciously trigger disturbing dreams. Previous studies have shown that the body can register internal disturbances in dreams before they appear as visible symptoms. For example, dreaming of fire may sometimes precede a fever.
Negative emotions like anxiety, often linked to digestive problems, may also carry into dreams. Nielsen explained, “We know that negative emotions from waking life can bleed into dreams. The same likely applies to gut disturbances during sleep.”
Interestingly, the study found no link between gluten intolerance and nightmares, possibly due to fewer gluten-intolerant participants or because gluten issues cause different emotional or physiological effects.
More Questions Than Answers
While the connection between lactose intolerance and nightmares appears strong, researchers caution it’s unclear whether people sleep poorly because they eat badly, or vice versa—or whether another unknown factor influences both.
Nielsen says further research is needed, ideally with larger, more diverse samples. He and his team are already planning follow-up studies.
Their “ideal experiment” would involve splitting participants—both lactose-intolerant and tolerant—into groups assigned to eat specific foods before bed. One group would consume regular dairy, another lactose-free dairy, to measure the exact effects on dreams and identify whether the cause is specific to those with lactose intolerance.
