Five Scientific Findings About Christmas

1. Singing together decreases stress and increases social bonding

Singing Christmas carols together is an important part of the Christmas tradition in many families. One study from Michigan has shown that this tradition can increase physical and psychological well-being as well as increasing social bonds between people that sing together (Keeler et al., 2015). In the study, the scientists investigated the neurochemistry and social flow of group singing. They found the group singing lead to a decrease of adrenocorticotropic hormone (ACTH), a marker of stress and arousal. Thus, group singing seems to decrease stress. Moreover, improvised group singing leads to an increase in oxytocin, a hormone that has been linked to social bonding in humans. This shows that singing together increase social bonding between the people that sing.

2. A Christmas spirit network in the brain

In this (somewhat ironically written) study, the authors used magnetic resonance imaging to localize the Christmas spirit in the human brain (Hougaard et al., 2015). To this end, they investigated 10 people who celebrated Christmas and 10 people without a Christmas tradition. Participants were shown Christmas-themed pictures while their brains were scanned in an MRI machine.

The result: People that celebrated Christmas showed increased brain activity when viewing Christmas-related pictures in the sensory motor cortex, the premotor and primary motor cortex, and the parietal lobule when compared to controls without a Christmas tradition. These brain regions have been associated with spirituality, somatic senses, and recognition of facial emotions in previous studies. The authors concluded that there is a Christmas spirit network in the brain, but also clearly remark that these findings should be interpreted with caution and that more research is needed to fully understand the magic of Christmas.

3. Spending money on gifts for other people can make you happier than spending it on yourself

Can money buy happiness? Maybe it can but in an unexpected way. Buying Christmas presents for all your loved ones can be expensive, but it might still be the best way to spend your money to promote your own happiness, according to science. In one study from 2008, the authors asked participants to rate their happiness in the morning. The scientists then gave each participant an envelope with money (either 5 dollars or 20 dollars) that they had to spend until 5:00 p.m. that day (Dunn et al., 2008).

Participants were then randomly assigned to different spending groups, e.g. there were told to spend the money on a bill, an expense, a gift for themselves, or a gift for someone else. After 5:00 p.m. the participants were called and had to report their happiness again. Independent of the amount that they could, participants that bought a gift for someone else showed the greatest increase in happiness in the afternoon. Thus, spending money to buy a gift for someone else actually makes you happier than buying a gift for yourself.

4. Heart failure and the holidays

Christmas can be taxing on the heart, emotional stress and unhealthy life choices can affect cardiac health. One 2016 study from Pennsylvania investigated whether Christmas was indeed associated with increased heart failures (Shah et al., 2016). To this end, the authors analyzed patient admissions to Einstein Medical Center in Philadelphia between 2003 and 2013. They found that Christmas was indeed associated with increased heart failure admissions. They concluded that emotional stressors, overeating, less exercise, and postponing medical appointments during holidays could potentially contribute to this increase in heart failure.

5. Holiday weight gain is on the rise

Christmas can be a time of overindulgence and is thus often associated with weight gain according to scientific studies. One 2000 study did show that Christmas was associated with an average weight gain of about 500g (Garrow, 2000). However, this value seems to be on the rise in the last two decades. A newer study in almost 3000 participants from Japan, Germany. and the U.S. found that in 2016, weight increased by 600g in U.S. participants, 800g in German participants and 500g in Japanese participants over the holidays (Helander et al., 2016).