My HormonologyFenesha, a Hormonology newsletter subscriber, asks: “I normally have a 28-day cycle with a period length of 5 days. Last month I experienced a 23-day cycle, with the same period length and regular ovulation time. What could have caused the shortened cycle?”

My answer:

There could be a variety of reasons why a typically 28-day cycle was shorter: The most common are perimenopause (which typically starts to occur to women in their mid-40s), medications and stress. Another factor, believe it or not, is proximity to a certain man or woman who changed your cycle. We all emit pheromones and, as I’m sure you’ve heard, women who spend a lot of time together (roommates, family members, sports team members) often have their menstrual cycles sync up. That’s because of these scentless pheromones in our sweat that act as chemical messengers. Research has also shown that pheromones in male sweat can alter your hormones in a similar way, causing a change in the number of days of your cycle.

All this said, any dramatic shift in your cycle is something to talk to a doctor about. So, if your usual 28-day cycle continues to be drastically different for three or more cycles, it’s time to visit your gyn.

Have a question of your own? For instance, how Hormonology works, which is the best week of your cycle to do an activity or how your hormones impact you in a certain way? Ask me! Send your question to gabrielle [at] hormonehoroscope.com. It could end up in the next Hormonology post!

Want to get the free Hormone Horoscope delivered to your email inbox? Submit your email address in the signup form at the top of this page!