Apparently, losing their virginity is high on the list for those with significant others, according to researchers who reviewed data from a federal health survey.

While June is the most common month for teen-agers to have sex for the first time -- be it in a casual summer fling or steady relationship -- sociologists from Mississippi State University say many teen-agers who are dating seriously choose December as the time to have sex for the first time.

"We call it the 'Santa Claus effect,'" says Martin Levin, lead author of the study, which is published in the current issue of the Journal of Marriage and Family.

The findings ring true to Becky Rose, a 19-year-old student at New York University.

"I'd say we're all fairly vulnerable and needy, and need someone to cling to and love," she says.

She says it's partly the stress of final exams, followed by the holidays that make her "more emotional" during the holidays. "Everything you see on TV has people kissing under mistletoe and 'Buy her a diamond -- she'll love you!'"

Whatever the reasons, experts say the holidays are the perfect time for parents to talk to their teen-agers about sex. "At the very least," says one of the expert, "maybe we should say, 'Leave the lights on.'"

(Agencies)