by Zoë Pollock

You're getting one all the time:

At a given moment, if you’re breathing through your nose, the lion’s share of the air is going in and out of one nostril, with a much smaller amount passing through the other. Every few hours, your autonomic nervous system, which takes care of your heart rate, digestion and other things you don’t consciously control, switches things up and your other nostril does all the heavy lifting for a little while. The opening and closing of the two passages is done by swelling and deflating erectile tissue – the same stuff that’s at work when your reproductive organs are aroused – up in your nose.