As the clock struck midnight, shouts rang out across Harvard Yard. Despite exams to come in nine hours, students bared it all in the spring incarnation of an age-old, clothing-optional tradition: Primal Scream.

The event, which takes place at midnight before the first exam of each semester, drew a diverse crowd to the Yard Thursday night. Daring undergraduates stripped down past their undergarments and sprinted around the Old Yard to the tunes of “The Final Countdown” and “Chariots of Fire,” performed by the Harvard University Band.

Though a number of students lined the freshman dorms in support of their classmates, Harvard affiliates were not the only spectators. Primal Scream drew viewers from across Cambridge and even from foreign nations.

“I think it’s pretty cool,” said Kan-Ju Lin, a Taiwanese post-doctoral student at MIT, of the scantily clad Harvardians. “I’ve never seen people running naked.”

Participants ranged from Primal Scream virgins to veterans.

“I’m halfway there,” said Edwin L. Whitman ’15, who has completed four of four dashes. “Spring’s always a smaller turnout but it’s the people who do it all the time or the seniors so it’s more fun.”

Unlike Whitman, not all of this semester’s screamers planned to run.

“It was so awesome,” Phebe J. Hong ’16 said. “It was totally spontaneous. I decided at the last minute—I just took everything off and I ran.”

The winter run is historically better-attended, and participants this spring were as sparse as clothing. Still, over one hundred students rose to the occasion for a lap to end this year’s reading period.

Primal Scream, which began in the 1960s as a communal, cathartic yell before the start of exams, neglected clothing in the 1990s when it went au natural. To this day, many students appreciate the break it offers in the midst of exam stress.

“It’s a tradition,” Brian W. Ventura ’16 said. “It’s a lot of fun… We’re stereotyped as being uptight but this is kind of a nice release.”

One lap was only the tip of the iceberg for a number of particularly excited nudists, who continued on in their birthday suits for a second lap or, in the case of one intrepid runner, a racy photo with John Harvard.

“There should be so much more skin,” Hong said.

Despite the influx of tourists gathering on the steps of University Hall for a glimpse of the action, no increase in Harvard University Police Department officers was noted. Securitas officers declined to comment.

—Staff writer Cordelia F. Mendez can be reached at cordeliamendez@college.harvard.edu. Follow her on Twitter @CrimsonCordelia.

—Staff writer Molly L. Roberts can be reached at mollyroberts@college.harvard.edu. Follow her on Twitter @MollyLRoberts.