Have you ever when you’re sick that one nostril gets stuffy more than the other? There’s a reason for that.

“Many people don’t realize that every four to six hours, one side of the nose becomes more congested, and the other side decongests,” explained otolaryngologist Michael Benninger to the Cleveland Clinic.

The nose has a natural cycle called the nasal cycle that causes the blood vessels in the turbinates to swell on one side of the nose, blocking the airflow. Doing extensive exercise or being sick usually causes one side of the nostril to be clogged over the other, periodically switching sides.

“The turbinates have these large veins inside them that can fill with blood, particularly when you’re lying down,” noted Benjamin S. Bleier, a sinus specialist at Mass Eye and Ear. “That will give you a sense of congestion on the side you’re lying on.”

There are a few things you can do to relieve congestion, according to Health:

  • Use a saline nasal spray or rinse to help loosen mucus and clear out your sinuses.
  • The steam from a hot shower, bath or steam machine can help to loosen phlegm and open airways.
  • Invest in a humidifier to add moisture to the air, which can help thin mucus.
  • Take over-the-counter decongestants or antihistamines to help reduce swelling and congestion.
  • Sleep with your head elevated.
  • Drink plenty of fluids.

“While nasal sprays with oxymetazoline or phenylephrine can be very helpful, they should be limited to three consecutive days,” warned Kathleen Kelly, an otolaryngologist at The Ohio State University Wexner Medical Center.

According to Kelly, overusing nasal sprays can lead to what’s called “rebound congestion,” where stuffiness becomes worse if you don’t continue using the medication.

See a doctor if your congestion is severe or does not improve with home remedies.