As someone who just returned from a trip to the mountains, I can answer to the fact that altitude affects almost everything in your body. Dizziness and fatigue were simply part of life above 10,000 feet for me. But does altitude affect your period too? Traveling to great heights might change some things about your menstruation cycle as well.
First, though, it's important to look at general ways altitude changes affect the body. Decreased physical performance, sensory abilities, and even mood or personality changes are common at altitude, according to the Army Public Health Center. In other words? Altitude changes are no joke, and they can affect the body and mind in some serious ways.
For women in particular, living at a higher altitude may cause some hormonal period changes. Hormone profiles during the menstrual cycle of women living at high altitude differed in some ways from those of women living at sea level, according to a study in the International Journal of Gynaecology and Obstetrics. Specifically, serum progesterone levels on three days out of the cycle were significantly higher for women who lived at sea level, as further noted by the study. That said, the study was conducted back in 1996, and it examined 20 women total. More current research is needed to fully understand the ways living at altitude can affect a menstrual cycle.
What if you're not living at elevation, but just vacationing at a high altitude for a few days? Temporarily traveling to a high altitude area can affect a menstruation cycle by making it shorter, longer, or irregular, as noted by the International Mountaineering and Climbing Federation. But to make matters more confusing, other factors including jet lag, exercise, and cold weather can also affect menstruation cycles, as further noted by the federation. So if you're on a skiing trip, for instance, it can be hard to say whether your irregular period was due to general travel stress, the cold, or the high altitude itself. There are so many possibilities.
Can brief exposures to altitude, such as when you're on a plane, change your period, too? Well, wonky periods are not uncommon when it comes to flying, but they may be altered by stress instead of altitude. "Even subtle changes to your daily pattern — getting up super early one day and then sleeping late the next — can have a small effect on your melatonin levels," said Dr. Anita Mitra in Quartzy. "So it’s less the flight, and more that the flight has taken you to another destination and time zone." The general stress of travel, rather than simply the altitude, may be the cause of your period-based changes.
That said, you don't have to give up on rock climbing or mountain hikes just because travel and altitude might affect your cycle. For the most part, these changes to the menstrual cycle are somewhat mild. Of course, if you have any health concerns whatsoever — say you're trying to conceive while on a trip to Peru or something — don't hesitate to reach out to your physician for advice. There are plenty of ways to manage your menses and live the high (altitude) life at the same time.