The Unexpected Enemy of Sleep: Which Foods Can Trigger Insomnia and Nightmares

That nightly glass of warm milk you drink to help yourself relax could actually be making your sleep worse. Scientists have uncovered a surprising link between late-night eating and the quality of our sleep and dreams.

A new study published in Frontiers in Psychology sheds light on how eating before bed may affect the brain and the content of our dreams.

What Did the Study Find?

The study involved 1,082 university students, with an average age of 20. Participants completed detailed questionnaires, including the Pittsburgh Sleep Quality Index and the Insomnia Severity Index, and also provided information about their eating habits and food allergies or intolerances.

• Foods that may disrupt sleep: Eating dairy products, desserts, spicy foods and meat before bed was associated with more frequent nightmares and insomnia. More than 24% of participants said such late-night snacks worsened their sleep.
• Healthier habits: Around 20% of respondents said that light evening snacks such as fruit, vegetables or herbal tea, on the other hand, improved the quality of their sleep.
• The lactose factor: Researchers found a strong correlation between lactose intolerance and nightmares. Among participants who reported that eating negatively affected their sleep, nearly 30% were lactose intolerant, compared with 19.5% among those who did not report such problems.

Why Can Eating Before Bed Trigger Nightmares?

The researchers, led by Dr. Tore Nielsen of the University of Montreal, believe the problem may stem from gastrointestinal discomfort.

When a person eats heavy foods or consumes something their body does not tolerate well, it can cause hidden or obvious gastrointestinal irritation during the night. Because physical sensations during sleep can influence brain activity, bodily discomfort may be incorporated into disturbing dream narratives, resulting in vivid, frightening dreams and awakenings accompanied by distress.

Researchers also found that late-night eating itself — regardless of the type of food — was associated with more disturbing dream experiences.

At the same time, people who rarely eat before bed tended to remember their dreams better, possibly because their nighttime rest was calmer and deeper.

Experts’ Takeaways

The researchers note that changing eating habits, particularly for people with food sensitivities or intolerances, could offer a simple way to reduce troubling nightmares and insomnia.

However, the study was based on questionnaire data and requires further large-scale research. Still, its findings may help explain why the age-old advice to “have some warm milk before bed” does not work for everyone.