There are plenty of old wives’ tales about food before bed. What to eat, what not to eat and whether you should eat all. Now, a new study from researchers in Canada is adding a point against eating cheese just ahead of going to sleep.

The team of scientists studied how diets influence our dreams. In a study that included more than 1,000 participants, 40% reported that certain foods impacted their sleep. One of the standout culprits? Cheese.

The dairy product was associated with some not-so-gouda effects. Specifically, cheese consumption was linked to folks reporting more nightmares than sweet dreams, especially if a participant was lactose intolerant.

Why? Well, it all comes down to digestion.

Cheese is challenging to break down. The amount of fat and protein each morsel of muenster contains means its journey through the digestive tract is slow. At night, we are also not well equipped to digest food. Sleep is an activity that requires your body’s attention in full to achieve its list of hearty benefits. Add in some complicated digestion to the mix, and the focus becomes split between two areas. This affects your sleep quality … and what you get out of it.

Notably, cheese isn’t the only dairy product to impact our sleep. A warm glass of milk before bed can have a benefit. It is easier to digest than cheese, and it possesses the amino acid tryptophan, which helps promote solid shut-eye.

Generally, sleep experts recommend avoiding meals at least two hours before bed. And, if you are lactose intolerant, reconsider dairy consumption of any kind before you hit the hay — it’ll save you the nightmare of a late-night trip to the bathroom.