Why do some symptoms of illness ONLY occur at night and in the early morning?

Question

I have been sick for the past few days, but my symptoms only occur at night. They have been pretty bad, including a bad cough, sinus aches and pains, and lots of sneezing. However, during the day at work, I feel basically no symptoms at all. Symptoms start at about 9:30 pm and are the worst when I wake up in the middle of the night and early morning.

I am interested in a detailed and scientific answer to this question. I have done a small amount of research on the topic and basically came up with nothing. If someone could possibly point me in the direction of a scholarly published journal article on the subject, that would be fabulous.

Answer 1

Different air pressure and temperature during night.