THE mamak stall at midnight is a Malaysian institution, and no one sitting over a bowl of maggi goreng at 11.30pm has ever truly believed it would give them nightmares.
But the warning that late night eating leads to bad dreams has been around long enough to have earned a certain respectability, trotted out by parents trying to discourage post-dinner snacking and by anyone who woke up after a heavy supper feeling unsettled.
Is there actually any truth to it?
Verdict:
FALSE
For most people, eating late at night does not directly cause bad dreams. The real story is considerably more interesting than a simple yes or no, and it involves the gut doing things the brain would rather not know about.
The most comprehensive study to date on food and dreams was published in the peer-reviewed journal Frontiers in Psychology in June 2025, by researchers at MacEwan University in Canada led by Dr Tore Nielsen, director of the University of Montreal's Dreams and Nightmares Laboratory.
The study surveyed 1,082 university students about their diet, food sensitivities, sleep quality and dream experiences, making it the largest and most rigorous investigation into the food and dreams question ever conducted.
The findings were striking, though not in the way the old wives' tale would suggest.
Around a third of participants reported experiencing regular nightmares, but only 5.5% believed that specific foods were directly affecting the content of their dreams.
What the study did find was a strong and consistent link between food sensitivities, particularly lactose intolerance, and nightmare severity.
Participants who experienced gastrointestinal symptoms like bloating, cramping and gas during the night were significantly more likely to report disturbing dreams, with the severity of their nightmares directly corresponding to the severity of their digestive discomfort.
"Nightmare severity is robustly associated with lactose intolerance and other food allergies," Nielsen said in a statement accompanying the study's publication. "These new findings imply that changing eating habits for people with some food sensitivities could alleviate nightmares."
The mechanism the researchers identified was indirect but logical.
When the digestive system was in distress during the night, the physical discomfort disrupted sleep, causing more frequent awakenings during REM sleep, the stage in which vivid dreaming occurred.
More awakenings during REM sleep meant more dream recall, and since the body was already in a state of physical discomfort, the dreams being recalled tended to be negative in tone.
In other words, it was not the food itself that caused bad dreams but the discomfort it triggered in the gut, which then bled into the emotional tone of whatever was being dreamt at the time.
Among participants who reported food affecting their dreams, desserts and sweets topped the list at 31%, followed by dairy at 22% and meat at 16%.
Spicy foods, a category of particular relevance to anyone who had ever eaten a generous serving of cili padi at midnight, accounted for 19.5% of reported nightmare experiences.
However, the study was careful to note an important confounding factor: people were more likely to remember eating something unusual or late if they then had a bad dream, meaning the reported associations could partly reflect memory bias rather than a true causal relationship.
A separate peer-reviewed study examining late night eating and sleep disruption found that eating within three hours of bedtime was associated with more nocturnal awakenings, which again increased the likelihood of dream recall and the chance of remembering unpleasant dreams.
The important takeaway was that for healthy individuals without food sensitivities, eating late at night was unlikely to produce nightmares in any direct or consistent way.
For those with lactose intolerance, known food allergies or particularly sensitive digestive systems, however, a heavy or dairy-rich meal before bed genuinely did appear to increase the odds of a disturbed and unpleasant night.
So the midnight mamak run was probably safe for most. Just maybe go easy on the extra cheese.
Sources:
1. https://www.frontiersin.org/
2. https://www.frontiersin.org/
3. https://www.sciencedaily.com/
4. https://pubmed.ncbi.nlm.nih.
5. https://pmc.ncbi.nlm.nih.gov/
