ELI5: When you have a cold, why does it always feel horrible in the morning and get better throughout the day?

Not a doctor, but I did just go to the doctor and had this explained to me. The reason you feel like shit in the morning is because you’ve been laying down all night, so the mucus just sits and builds up instead of draining. The sore throat is caused by infected mucus resting on the throat throughout the night, causing inflammation.

Explain Like I`m Five: good questions, best answers.