jumpYou know that moment when you hear a sudden, loud “bang!” out of nowhere–and you jump with surprise?

That’s your body’s acoustic startle response, which is basically your inner alarm telling you, “Hey, it sounds like something bad could be happening, so let’s be on alert right now.”

Well, here’s something interesting to learn about your acoustic startle response:

According to a new study in the journal Behavioural Brain Research, your acoustic startle response–how easily you’re startled by sudden noises–fluctuates based on where you are in your monthly cycle.

Specifically, you’re more easily startled by unexpected sounds in your premenstrual Week 4.

The researchers chalk it up to you being in a more negative frame of mind due to a plunge in estrogen, which makes you more aware of–and afraid of–potentially threatening situations.

However, this isn’t the end of the story….

The researchers discovered that you’re also more jumpy from sudden noises during ovulation–which occurs in the last few days of your Week 2 (which is Day 13 to 15 in a 28-day cycle).

During this phase of your cycle, estrogen is as high as it gets all cycle long. Which is the total opposite of your hormone levels in your premenstrual Week 4.

So, what’s going on?

The researchers believe it may come down to two factors:

During ovulation, high estrogen is making your hearing ability sharper, allowing you to hear things you might miss in other weeks of your cycle.

What’s more, the high level of this hormone is amping up brain arousal, which means you’ve got a lot more energy, which can make you antsy, anxious and, as this study points out, more easily startled by unexpected bangs, pops and screeches.

What can you do with this information?

Well, it’s kinda hard to control your startle response. But, when you find yourself jumping with fear from a loud noise, you can take a peek at where you are in your menstrual cycle and, if you’re ovulating or in your premenstrual Week 4, you can reassure yourself that it’s just hormones making you more on edge.

And, if you’re curious to test this study yourself with your own experiment, you can find a woman who’s in the tail end of her Week 2 or in her premenstrual Week 4 and make a loud noise near her–like dropping a book on the ground or clapping hard–and seeing what her response to it is. (I’m certainly not suggesting you torture your friends–especially the premenstrual ones–by toying with their startle response. But, hey, if it’s for science….)

If you notice any differences in your–or a friend’s–acoustic startle response across the menstrual cycle, let me know. I’m curious what you find out!

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