Averaged together, however, the results showed that overall the circadian clock does affect smell, and that the times when the children’s noses were most sensitive tended to correspond to the evening, with an average peak of 9 p.m.

[...] Smell was at its lowest ebb, intriguingly, from about 2 a.m. to 10 a.m.

— Read more at The Circadian Clock in Your Nose at The New York Times.