Want to avoid the holiday season blues? Consider saying “bah humbug” to eggnog and peppermint cookies. As announced in Medical Hypotheses, researchers from the University of Kansas say there is enough existing scientific literature to strongly suggest that excessive consumption of added sugars increases vulnerability to depression. Added sweeteners are the extras pumped into foods and drinks by food manufacturers, as opposed to naturally occurring sources of sweetness.

Why? Too much sugar can trigger depressogenic physiological processes, including brain inflammation, insulin resistance and disruption of the gut microbiome. Couple these bodily disruptions with holiday stress and wintertime’s dwindling sunlight (yes, the seasonal affective disorder that comes with sunset before 5 p.m. can indeed be sad), and you may have an unhealthy recipe for poorer mental health.

See also: Nutrition Facts Panel Puts Spotlight on Added Sugars