According to political pundits, this US Presidential election has turned “historical.” And by historical, they likely mean exceptionally dismal and noxious. So no one should be surprised that the election is stressing people out.

According to an annual poll on the stress levels of the country, the American Psychological Association reports that 52 percent of adults are “somewhat” or “very” stressed by the battle for the Oval Office. That mental anguish is felt about equally across party lines, with 59 percent of Republicans and 55 percent of Democrats registering as stressed. Women and men are also equally stressed, at 52 and 51 percent, respectively.

Data from the online poll, conducted between August 5 and August 31, 2016, offer a few hints at the factors that are ratcheting up election anxiety. The poll includes data from 3,511 US adults and is weighted to reflect national demographics. The APA found that social media usage boosted election stress. Of those who use social media, 54 percent report being stressed by the campaigns, while, among those who abstain from such online chatter, only 45 percent fret over the political fray.

Age is also a factor. “Matures” (people aged 71 and over) and “Millennials” (aged 19 to 37) are the most likely to say they were stressed.

Social media usage clearly increases political anxiety, Lynn Bufka, APA’s associate executive director for practice research and policy, told Ars. About 38 percent of those polled said they were stressed by the political and cultural discussions on social media, which easily become hyperpartisan and uncivil.

The age breakdown was harder to explain and “surprising,” she added—at least for the older crowd. The finding that Millennials are stressed by the election makes sense because they tend to be heavy social media users, and they’re simply young. They haven’t built up mental safeguards against stress yet.

“And this is why [the data] is particularly surprising with the ‘Matures’,” Bufka said. “As we get older we learn how to roll with things... for the Matures, they’ve seen a lot in their lives,” she explained, such as job changes, deaths of loved ones, serious health issues, and financial struggles, not to mention political turbulence. “They know what the big things are and what the big things aren’t,” she said. They’re usually the least flappable.

Though the data doesn’t provide a definitive explanation as to why this election has rattled them, Bufka has some theories. She speculates that the tenor of the campaigns may seem more offensive or upsetting to an older crowd. “Matures” may also be stressed about the futures of their children and grandchildren. Lastly, neither candidate has emphasized issues important to the elderly—which, it's worth noting, tend to have high voter turnout.

While the breakdown of the stress data offers some insights, the bigger picture of political-based stress is foggy. The APA has been gauging American’s stress level annually for a decade, noting that the economy, work, and money are usually the top stressors for Americans. But this is the first time that the APA specifically asked about election-driven stress. By the numbers, the election elbowed into the top stressors, alongside the economy, work, and money. But it’s impossible to assess from the past polls if this historic election is historically stressful.

One fact that might bolster the argument that this Presidential election is exceptionally stressful is that it’s between the two most unpopular major-party candidates in the more than 30 years of polling. In a recent survey of registered voters, the candidates came in with the all-time highest unfavorable ratings: Hillary Clinton at 59 percent and Donald Trump at 60 percent. (Coming in third was George H.W. Bush’s popularity in July 1992 as he was to losing his re-election bid.) A recent Pew Poll found that the majority of voters are “disgusted” and “frustrated” with this election.

On the other hand, scientists and the media have noted political stress many times in the past. In 2004, the Washington Post reported that the country was gripped with PEAD (Pre-Election Anxiety Disorder) amid the battle between George W. Bush and John Kerry. And since then, researchers have noted that political participation alone can boost stress levels. In one 2011 study, scientists reported that on election days, voters’ cortisol (a proxy for stress responses) spike to five-times their normal levels. And simply going to the polls can be stressful, too, as another study found that voting at home could keep cortisol levels steadier.

But even after an election is over, our mental suffering may not be. In 2008, researchers found that John McCain backers had increased cortisol levels after the election results were announced, whereas Barack Obama supporters had stable levels.

Historic stress levels or not, this election’s impact on our mental health isn’t good. Prolonged stress can lead to mood disorders and stomach troubles, plus it dampens the immune system, potentially egging on infections and long-term health problems. To beat back election stress as we head into the final stretch and the last debate on Wednesday, the APA recommends that voters: