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Contrary to popular belief, instead of boosting the mood for holiday cheer, eating sweets this Christmas can actually increase a person's risk of having holiday depression.

This is supported by a new study published in the journal Medical Hypotheses by researchers from the University of Kansas who analyzed a wide variety of data on the physiological and psychological effects of consuming added sugar, which is present in holiday desserts. They also compared the effects of eating too much sugar around the holidays to that of drinking too much alcohol.

Study co-author Stephen Ilardi, PhD, an associate professor of clinical psychology at the University of Kansas noted that sugar, like alcohol is basically pure calories, pure energy, non-nutritive and very toxic at high doses.

"We're learning when it comes to depression, people who optimize their diet should provide all the nutrients the brain needs and mostly avoid these potential toxins," he added.

Nearly half a million Americans are prone to seasonal depression. An article in Forbes cited psychological reasons why people fall into depression during this season such as the increase in stressful demands, inability to sidestep family issues, and difficulty managing expectations. This comes with increased feelings of sadness, guilt, inadequacy, overwhelm, alienation, and unworthiness.

Moreover, HuffPost reports that changes in eating and drinking habits, increasingly cold and dark winter days, and constant reminders of others' happy seasons which additionally serve as a painful reminder of the happiness and love that's lacking in one's life, are the reasons why December can be a particularly difficult time of year for some people.

Eating a box of cookies, like drinking several glasses of wine, might provide a temporary feeling of comfort and joy, but can make a person feel worse overall if regularly consumed in large quantities.

Sweets act like a drug, according to Ilardi. "They have an immediate mood-elevating effect, but in high doses they can also have a paradoxical, pernicious longer-term consequence of making mood worse, reducing well-being, elevating inflammation and causing weight gain."

The study co-author also noted that a "large subset of people with depression have high levels of systemic inflammation," which pushes the brain into a state of severe depression.

Ilardi also pointed out it still varies from one person to another whether what amount could count as too much. However, as a rule of thumb, he suggests sticking to the guidelines set by the American Heart Association, which recommends limiting the daily intake of added sugar to 100 calories for women and 150 calories for men, to avoid the physical and psychological repercussions.

Psychom further suggests that one should recognize the fact that the holiday blues is real and much more common than what everyone thinks. Second, one should always be kind to themselves and avoid beating oneself up for feeling so. And finally, take a few minutes to educate oneself about some of the major causes and best remedies for the holiday blues.

As for the holiday season in general, experts say a good way to battle holiday depression is for family and friends to watch out for their loved ones.