Is period syncing real?

Do mothers and daughters really sync?

Quick summary

• Period syncing is the belief that people who menstruate will align their cycles when spending time together.
• However, there is little scientific evidence supporting period syncing, and most experts consider it a myth.
• Using period tracking tools can help them better understand their own patterns rather than relying on others' cycles.

Rated 4.8

Empower your teen today. Subscribe them to luna.

Find out more

Let’s explore an interesting concept you may have heard about – period syncing, or the idea that menstruators’ cycles align when they spend a lot of time together.

Period syncing: what is it?

This concept dates back to the 1970s when researchers suggested that pheromones (natural chemicals our bodies emit) could influence each other, leading to synchronised menstrual cycles.

Recently, we've noticed a resurgence on social media and it's become a bit of a TikTok trend.

In simpler terms, the theory is that if your teen spends significant time with a female (AFAB) family member or friend, they would eventually have their periods at the same time.

Teens on the luna app also use the term "bluetoothing" periods a lot, particularly in the case where they have not yet started and so think their first period will be bluetoothed to them if they spend a lot of time with a mother, sister, or close friend who has periods.

Is period syncing real?

Despite this early research, there hasn’t been much scientific follow-up to confirm the theory. Current evidence is minimal, and scientists largely consider period syncing a myth.

While the idea can seem fun and relatable, it’s much more likely to be coincidence. Given that the average menstrual cycle lasts around 28 days, it’s inevitable that cycles will overlap at some point.

When do periods sync?

There’s no definite answer to this question. As mentioned earlier, scientific studies have yet to prove that menstrual syncing is real. 

While it’s a widespread belief that people who spend a lot of time together start to have their periods at the same time, there’s no solid evidence that hormones work that way.

But if your teen asks when they might start syncing with their friends or even their mother, you can gently explain that:

• it’s normal for cycles to overlap occasionally due to chance
• stress, diet, sleep, and exercise can affect period timing
• a teen’s menstrual cycle can take years to become regular – this might make syncing seem more likely
• being around others who menstruate doesn’t change your cycle, but shared environments and routines might cause cycles to align by coincidence

Let them know it’s okay to ask these questions and that curiosity about their body is healthy.

Supporting your teen’s understanding

Your teen might find comfort in the idea of sharing their period experience with others, and that’s perfectly natural.

However, it’s a good idea to remind them that everybody is different, and their cycle follows its unique rhythm. 

This can also be reassuring to them, if they find that their body doesn't perfectly match up to a friend or family member's.

As best you can, encourage them not to use anyone else’s cycle as a guide for predicting their own.

Instead, consider introducing them to tools like period trackers that help them identify their individual patterns – luna has a great, straightforward tracking feature which is tailored to teenagers.