Christmas hormones drive even sane people slightly cuckoo, shows study.
According to Mike Ludwig from the University of Edinburgh, who wrote in Journal of Neuroendocrinology earlier this year, come December, "it is inevitable that, once again, we will again totally surrender to the effects of our Christmas hormones."
Ludwig does goes so far as describing the effects of the festival as "traumatic".
In the new study, Robert Lustig from the University of California at San Francisco has described just how much those "Christmas hormones" take hostage of our bodies.
Speaking on ABC's 'Good Morning America', Lustig said that the season is fraught with hormonally-driven behaviour, driving irrational actions and thoughts.
"Certainly, it brings out the best and worst of us in every which way," the Daily Mail quoted Lustig, a neuroendocrinologist and professor of paediatrics as saying.
He also said that the potent mix of cortisol, serotonin and dopamine are at play over the holiday season.
While the togetherness of Christmas, ultimately what the day is all about, fosters surges in the happiness hormone, serotonin, the build up is characterised by high levels of stress, or cortisol.
Therefore, the more that dopamine is triggered, the larger the amounts of food that are needed to feel the hormone's pleasurable effects, which leads to over-eating, peaks and troughs of insulin and sugar highs and lows.
In the meantime, high stress levels see rises in blood pressure, suppression of the immune system and increased sugar production, he told the show.
It's only to be expected that mood swings and arguments may ensue.
It comes as no surprise that close to 70 percent of Americans say they are fatigued by Christmas, says the American Psychological Association.