Eating added sugars -- common in so many holiday foods -- can trigger metabolic inflammatory and neurobiological processes tied to depressive illness said the study from a team of clinical psychologists at the University of Kansas published in the journal Medical Hypotheses. Coupled with dwindling light in wintertime and corresponding changes in sleep patterns high sugar consumption could result in a perfect storm that adversely affects mental health. For many people reduced sunlight exposure during the winter will throw off circadian rhythms disrupting healthy sleep and pushing five to 10 per cent of the population into a full-blown episode of