Halloween is now the second-biggest consumer-spending holiday in the US (after Christmas), which makes you wonder—how did a holiday based on dressing up and being scary achieve not only massive national appeal, but now international demand (yep, the Americanized version of Halloween has been successfully exported to countries around the globe)?

The American version of Halloween has an interesting evolution. Early Puritan settlers were staunchly against Halloween and considered it far too dark and devilish. However, throughout the 19th century, immigrants from Ireland and Scotland introduced the States to the ancient Celtic festival of Samhain (https://en.wikipedia.org/wiki/Samhain), which involved wearing scary costumes and lighting fires to scare away tormenting spirits.

Being the “melting pot” that is the US, Halloween became a mix of traditions from Samhain and the Christian “All Saints’ Day,” when Saints are honored and people gather to pray for the recently departed. Rituals like wearing costumes and dark robes, lighting candles, and offering gifts (or treats) were mixed and reimagined over and over, resulting in the traditions Americans now know and love, like trick-or-treating, bobbing for apples, and dressing up in costumes—which can range from a traditional scary witch to slutty nurse (for a good look at the increasingly sexy costumes, check out Elizabeth A. Grater’s The Rise of “Slut-o-ween”: Cultural Productions of Femininity in Halloween Costumes http://pqdtopen.proquest.com/doc/1016161040.html?FMT=ABS). The mixture of traditions slowly solidified into the very consumer friendly and festive Halloween we have today, complete with candy, costumes, mischief, and mayhem. It became an evening to be someone else, to dip your toes into the taboo, and in doing so, remember who you are, or who you wish you were.

But Halloween is more than just a chance to dress up, this time of year evokes a powerful emotional response for many people. When the sun starts setting closer to 4:00pm instead of 9:00pm, and a cool chill enters the air, and pumpkin recipes dominate the menu, we can’t help but feel this tingle down our spine and tug on our heart as waves of nostalgia overwhelm us. Our whole body feels activated and the world seems veiled behind the new “scare filter”: every cornfield we pass seems to whisper, “Come inside,” and spider webs are no longer a nuisance, but a decoration. This is a special time.

This time of year conjures such a strong response for a number of reasons. While Christmas and Thanksgiving, along with most of the other traditional American holidays, are focused on family, Halloween is all about friends. No family stress, no pressure to put on a good show for your in-laws or relatives—Halloween is when you can let loose with your friends and embrace your dark side. At the same time, Halloween gives you a space and a place where feeling scared is not only acceptable, but also desirable. For those of us that walk around constantly putting on a “brave” face while managing abstract fears with no apparent solutions (climate warming, social security, the November election), being able to walk through a haunted house, scream your head off, and come out the other side can feel incredibly cathartic.

Collectively, this time of year is loaded with sensory stimuli that activate our richest memories: the smell of cider, pumpkin spice, and even the thick cake makeup you can buy from the dollar store, “This is Halloween” and “The Monster Mash” popping up on playlists (and my favorite new classic “Werewolf Bar Mitzvah” https://www.youtube.com/watch?v=A6V2oCX3Hn4), watching all of your favorite shows roll out their spooky episodes (which for many series are among their best, http://www.complex.com/pop-culture/2012/10/25-best-halloween-tv-episodes/charlie-brown), and the instinctive, visceral gag response to diving your hand inside a freshly carved pumpkin and pulling out the slimly seeds and guts. And then there is the candy. ALL THE CANDY. Candy that isn’t readily available year round (candy corn!) suddenly appears, and as the sugary goodness hits our taste buds, we’re transported back to when we were just seven years old, dressing up as Wonder Woman or the devil and running around the neighborhood unsupervised for the first time. Powered by sugar and protected by five-dollar plastic masks, my sister and I were invincible (I’m Wonder Woman):

The combination of friends, thrills, chills, and spooky things thrusts our bodies, namely the emotional processing centers in our brains (amygdala, insula, prefrontal cortex, hippocampus), into a perfect state for encoding layered and strong memories. We store intense emotional experiences with more detail and importance than non-emotional experiences—it’s each of our body’s way of making sure we remember what makes us feel good (and to seek it out more) and what makes us feel bad (to stay away). So next year, as soon as you catch a glimpse of that smiling jack-o’-lantern, your body will remember, and maybe you’ll be ready to scream.

So there you have it, Halloween is loaded with intense emotional triggers: the nostalgia of Halloween’s past, the excitement and exhilaration of dressing up in costumes with friends, the thrill of anticipating when someone might jump out and go, “BOO!,” and, of course the activation of our reward systems via the consumption of delicious candy. It is a perfect recipe for strong, positive emotional memories, so everyone sing with me, “This is Halloween. This is Halloween. Everybody SCREAM!”