The period from late November through January in the US includes the country's busiest travel day, as well as the most calorie-drenched meal Americans eat, and what's generally regarded as the drunkest night of the year.

Holiday gatherings can change testosterone, cortisol, and other hormone levels

Cortisol, our primary stress hormone, may go up and down a lot over holiday breaks, Robin Edelstein, an associate professor of psychology who studies hormones and relationships at the University of Michigan, told Insider.

"For some people, going home could be this very comforting experience, which could lower stress, decrease cortisol," she said.

But that is not always the case. For example, imagine you're about to miss your flight, and you're running for the gate.

"Cortisol would go up really quickly," Edelstein said.

This kind of acute stress can influence the hormones of significant others, too. During an argument, one person's cortisol spike could make their partner's skyrocket, which scientists have discovered is often a hallmark of relationship troubles. Conversely, the presence of a trusted partner could help another person feel less stressed when traveling. It all depends on the dynamics of the relationship, the situation, and the people involved.

The holidays can also shift sex hormone levels, which may prompt temporary changes in testosterone in both men and women.

"If you think of sort of the warm, happy, relaxing holiday weekend, that could probably lower testosterone," Edelstein said. "But to the extent that there is competition and conflict, it might increase it."

Read the full article at Business Insider.