Obstructive sleep apnea happens when the muscles in the back of your throat relax, according to the Mayo Clinic.

 

When these muscles relax, your airway narrows and you’re unable to breathe properly, the Mayo Clinic states. This can lower the oxygen levels in your blood. When this happens, your brain wakes you up so you can take a breath.

 

When you wake up, it’s usually so brief that most people don’t remember it, the Mayo Clinic states. These disruptions prevent you from getting a good night’s sleep and can leave you feeling tired the next morning.