Maybe I’m alone in this, but it seems to me that after the last month of intense peace and good will to men, post-Christmas depression feels karmically fair. How can any one person feel that much joy without spending at least a week paying for it? This year I decided to do a little research into the causes of this phenomenon, so as to better understand its scientific roots. The following are the five most prominent results of my study.

1. We cannot exist outside of a sugar coma. Mix tantalizing new Pinterest dessert ideas with old family traditions and by the 26th none of us can be trusted to complete any tasks with any level of importance or intellectual component. It’s all fun and games until the frosted sugar cookies turn into muffin tops. The only thing left is to set reasonable goals for the New Year, such as “Never eat sugar again.” Faced with that pleasant future, and with sugar still on our addicted brains, who could blame us for wishing we could rewind to yesterday?

2. We lack the familiar hustle and bustle. Whether it be parties with family, white-elephant gift exchanges with friends, or lines at the mall, by Christmas day we evolve into a Darwinian species with heightened ability to survive fast-paced events day after day. When wrapping paper is strewn across the floor and the doorbell has stopped ringing, we don’t know how to exist in a room with less than fifteen people. It is no longer acceptable to spend time with family. It’s hard to be lonely.

3. There is too much darkness. Everything from our rooftop to our dogs has been decked in strands of tiny lights for some time now, and our eyes have grown accustomed to the constant glow. As the lights turn off, it takes our pupils an unexpectedly long time to adjust to our newfound darkness. Our houses are ugly now, if we can find them at all in the unrecognizable blandness of the neighborhood. Trees are green. Just green. The only lights left inside are those coming from lamps and light fixtures. Come January or February, we will adjust to the new reality of yellow and white lights instead of green and red ones, but until then, we should expect to feel a little down. After all, light not only guides our eyes, but also our souls.

4. We don’t know the words anymore. As a society, we have spent a collective seven billion hours over the last 25+ days singing and listening to various versions of the same ten carols. On December 26th every year, the radio stations pull the rug out from under us and we are left with songs we used to know, or new songs we’ve never heard before, and we don’t know how to sing along. A natural sense of misdirection sets in, because we like to know the script of our lives. We don’t know the words anymore. What does that mean for the coming months?

5. Without gifts, what is there to live for? For one month of the year, we force ourselves to set time apart from our busy work schedules to think about others. That is, in truth, unsustainable for more than one month. But after all the gifts are exchanged, we are left feeling void of the satisfaction giving gifts brings to our souls. If only this uplifting, tradition of giving gifts of time and thought to each other could last longer than the Christmas season.

I’ll summarize my study with the conclusion that depression after Christmas is inevitable. The only ways to avoid days–possibly months–of dreariness would be to committing to allowing ourselves moderate amounts of happy-food, staying social, letting light enter our lives daily, singing the songs that bring us joy, and taking the time to think about others. And let’s be realistic: those things can only be accomplished in December.