Here are some of the people trying to fix period education across North America

True or false? People who get periods can sync up their menstrual cycles with their friends. 

"True," said Toronto resident Sarah Hall.

"I think that's false," said Tovan Lew, another Torontonian. 

Period syncing isn't real. Experts have pointed out for years that there's no biological evidence for it. 

"If it were true, I would tell you," says Dr. Jen Gunter, a Canadian American gynecologist whose recent book Blood looks at the myths and shame around menstruation. "That's something that really rocks a lot of people's worlds." 

In fact, anecdotal experiences of cycle-syncing likely boil down to math: If one person gets their period every three weeks, while another gets theirs every five weeks, there will eventually be overlap in the cycles.  

It's just one of dozens of period myths circulating online. Many such myths have been around for ages. But platforms like TikTok and Instagram are causing them to spread faster and reach a wider audience. A quick scan on the app will pull up videos of young women telling their audiences that papayas induce periods — one video has over three million views — even though there's no evidence backing that claim.

Or that organic tampons, while pricey, are safer than regular tampons. (Experts say they are about the same, safety-wise.)

From new books to university groups and OB-GYNs appearing on social media, a movement of people is trying to change how we talk — and learn — about our periods.

"Why are our schools not teaching people basic biology? We need to do a better job at a public health level, teaching people the basics," said Gunter.

Another corner of social media advocates for "free bleeding," where people toss away their period products — tampons, pads, menstrual cups — and let the blood flow. Some influencers say free bleeding lessens cramps and can shorten periods.

"We have no data to say that menstrual products cause pain or cramping, or they increase your flow. That is all completely made up," Gunter said. 

"The harm is people thinking that if they don't use menstrual products, that their terrible cramps are going to go away, and so they sit at home bleeding as opposed to getting medical care," she said. 

Women's health research has long been underfunded, and the science behind periods can seem particularly thin. Leah Hazard, midwife and author of the book Womb, told the New Yorker that during a review of scientific studies she found about 400 studies on menstrual fluid — compared to more than 15,000 about semen. She blamed the period "yuck factor" for dissuading related research.