People are slightly taller in the morning than at the end of the day.
Why it is true
During the day, gravity compresses the cartilage between the spinal vertebrae. At night, while sleeping horizontally, this cartilage expands again, restoring height.
Source: Chiropractic Journal
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.